TESTING MILK 

AND ITS PRODUCTS 



FABBINGTON AND WOLL 




Book : 






i"*- — 



CopghtN". 



/4/i 



COPYRIGHT DEPOSIT. 




DR. S. M. BABCOCK 
Inventor of the Babcock Milk Test 



TESTING MILK 

AND ITS PRODUCTS 



A MANUAL FOR DAIRY STUDENTS, CREAMERY AND 

CHEESE FACTORY OPERATORS, FOOD CHEMISTS, 

AND DAIRY FARMERS 



BY 



E H. FARRINGTON and F. W. WOLL 

Professor in Charge of Dairv School Professor of Animal Nutrition 

Un.vers.ty of Wisconsin Un.vers.ty of Caufornia 



With Illustrations 



TWENTY-THIRD REVISED AND ENLARGED EDITION 



MADISON, WIS. 

MendSta Book Company, 

1916 

ALL RIGHTS RESERVED 



cf 2 5"^ 



Copyright, 1897, 1899, 1901, 1904, 1909, 1911 and 1913. 
By E. H. FARRINGTON and F. W. WOLL 




^<S 



K ■ 

CANTWELL PRINTING COMPANY 
MADISON, WIS. 



5EC-6I9I5 



PREFACE TO FIRST EDITION. 



The present volume is intended for the use of dairy students, 
factory operators, dairymen, food chemists, and others interested 
in the testing or analysis of milk and its products. The subject 
has been largely treated in a popular manner; accuracy and 
clearness of statement, and systematic arrangement of the sub- 
ject matter have, however, been constantly kept in mind. The 
aim has been to make the presentation intelligible to" students 
with no further training than a common-school education, but 
their work will naturally be greatly lightened by the aid of an 
able teacher. 

Complete directions for making tests of milk and other dairy 
products are givem; difiiculties which the beginner may meet 
with are considered in detail, and suggestions offered for avoid- 
ing them. It is expected that a factory operator or practical 
dairyman, by exercising common sense and ordinary care, can 
obtain sufficient knowledge of the subject through a study of 
the various chapters of this book to make tests of milk, cream, 
etc., even if he has had no previous experience in this line. 

For the benefit of advanced dairy students who are somewhat 
familiar with chemistry and chemical operations. Chapter XIY 
has been added giving detailed instructions for the complete 
chemical analysis of milk and other dairy products. The detee- 
tion of preservatives and of artificial butter or filled cheese has 
also been treated in this connection. 

As the subject of milk testing is intimately connected with 
the payment for the milk delivered at butter- and cheese fac- 
tories, and with factory dividends, a chapter has been devoted 
to a discussion of the various systems of factory book-keeping, 
and tables greatly facilitating the work of the factory secretary 
or bookkeeper have been prepared and are included in the 
Appendix. 

Madison, Wis., October 1, 1897. 



PREFACE TO TWENTY-SECOND EDITION. 



Each year that passes brings some valuable contributions to our 
knowledge of the subjects treated in this book and a frequent re- 
vision of it is therefore desirable. The present edition contains 
descriptions of methods and apparatus that have stood the test of 
actual use during the past few years; the new information pub- 
lished since the last revision of the book has been carefully sifted, 
and what was deemed of sufficient importance has been incorpo- 
rated in such detail as the scope of the book permitted; many 
changes and additions suggested by the experience of the authors 
have also been introduced. The book has, in brief, been subjected 
to a renewed critical examination and careful revision. 

The general adoption of the book as a text or reference book in 
American dairy schools, as well as the favorable reception which it 
has been accorded by the dairy public in general, will, it is hoped, 
be further justified by the present revision. Acknowledgment is 
due to the following parties for loan of electrotypes, viz. : Cream- 
ery Pkg. Mfg. Co., Chicago, 111.; Vermont Farm Machine Co., 
Bellows Falls, Vt.; D. H. Burrell & Co., Little FaUs, N. Y.; Henry 
Tromner, Philadelphia, Pa.; Torsion Balance Co., New York City, 
and Marschall Dairy Laboratory, Madison, Wis. 

Madison, Wis., Oct. 1, 1913. 



TABLE OF CONTENTS. 



PAGE 

Introduction 1 

Chap. I. Composition of milk and its products 10 

Chap. II. Sampling milk 23 

Chap. III. The Babcock test — Milk 28 

A. Directions for making the test 29 

B. Discussion of the details of the test 37 

Chap. IV. The Babcock test — Cream 75 

Chap. V. The Babcock test — Other milk products 90 

Chap. VI. The lactometer and its application 102 

Chap. VII. Testing the acidity of milk and cream 119 

Chap. VIII. Testing the purity of milk 137 

Chap. IX. Testing milk on the farm 142 

Chap. X. Composite samples of milk 160 

Chap. XI. Cream testing at creameries 176 

Chap. XII. Calculation of butter and cheese yields 187 

Chap. XIII. Calculating dividends 203 

Chap. XIV. Chemical analysis of milk and its prod- 
ucts 217 

Appendix -_^ 259 

Table I. Composition of milk and its products. 

Table II. State ana city standards for dairy products. 

Table III. Quevenne lactomet3r degrees corresponding to 
the scale of the IN. Y. Board of Health lactometers. 

Table IV. Value of ^ for specific gravities from 

1.019 to 1.0369. 

Table V. Correction table for specific gravity of milk. 

Table VI. Per cent, of solids not fat, corresponding to 
to 6 per cent, of fat and lactometer readings of 26 to 36. 

Directions for the use of Tables VII, VIII, IX and XI. 

Table VII. Pounds of fat in 1 to 1,000 pounds of milk 
testing 3 to 5.35 per cent. 

Table VIII. Pounds of fat in 1 to 1,000 lbs. of cream test- 
ing 12.0 to 50.0 per cent. fat. 



vi Testing Milk and Its Products. 

Table IX. Amount due for butter fat, in dollars and cents, 
at 12 to 2o cents per pound. 

Table X. Eelative-value tables. 

Table XI. Butter chart, showing calculated yield of but- 
ter, in pounds, from 1 to 1,000 pounds of milk testing 3.0 to 
5.3 per cent, of fat. 

Table XII. Overrun table, showing pounds of butter from 
100 pounds of milk. 

Table XIII. Yield of cheese, corresponding to 2.5 to 6 per 
cent, of fat, with lactometer readings of 26 to 36. 

Table XIV. Comparisons of Fahrenheit and Centigrade 
(Celcius) thermometer scales. 

Table XV. Comparison of metric and customary weights 
and measures. 

Table XVI. Specific gravity and weight of one gallon of 
cream, arranged according to the per cent, of fat. 

Suggestions regarding the organization of co-operative 
creameries and cheese factories. 

Constitution and by-laws for co-operative factory associa- 
tions. 
Index 291 



Testing Milk and Its Products. 



INTRODUCTION. 



The need of a rapid, accurate and inexpensive method 
of determining the amount of butter fat in milk and 
other dairy products became more and more apparent, 
in this country and abroad, with the progress of the 
dairy industry, and especially with the growth of the 
factory system of butter and cheese making during the 
last few decades. So long as each farmer made his own 
butter and sold it to private customers or at the village 
grocery, it was not a matter of much importance to 
others whether the milk produced by his cows was rich 
or poor. But as creameries and cheese factories mul- 
tiplied, and farmers in the dairy sections of our coun- 
try became to a large extent patrons of one or the other 
of these, a system of equitable payment for the milk 
or cream delivered became a vital question. 

I. Nearly all the creameries in existence in this coun- 
try up to about 1890 were conducted on the cream- 
gathering plan : the different patrons creamed their 
milk by the gravity process, and the cream was hauled 
to the creamery, usually twice or three times a week, 
where it was then ripened and churned. The patrons 
were paid per inch of cream furnished. This quantity 
was supposed to make a pound of butter, but cream 



2 Testing 3Iilk and Its Products. 

from different sources, or even from the same sources 
at different times, varies greatly in bntter-prodiicing 
capacity, as will be shown under the subject of cream 
testing (203^). The system of paying for the number 
of creamery inches delivered could not therefore long 
give satisfaction. 

The proposition to take out a small portion, a pint or 
half a pint, of the cream furnished by each patron, and 
determine the amount of butter which these samples 
would make on being churned in so-called test churns, 
found but a very limited acceptance, on account of the 
labor involved and the difficulty of producing a first-class 
article from all the small batches of butter thus ob- 
tained. 

2. The introduction of the so-called oil test churn in 
creameries, which followed the creamery-inch system, 
marked a decided step in advance, and it soon came 
into general use in gathered-cream factories (202). In 
this test, glass tubes of about % inch internal diameter 
and nine inches long, are filled with cream to a depth 
of five inches, and the cream is churned; the tubes are 
then placed in hot water, and the column of melted 
butter formed at the top is read off by means of a scale 
showing the number of pounds of butter per creamery 
inch corresponding to different depths of melted but- 
ter. While the oil test is capable of showing the differ- 
ence between good and poor cream, it is not sufficiently 
accurate to make satisfactory distinctions between dif- 
ferent grades of good and poor cream.^ As a result, 



iJRefers to paragraph numbers. 

2 Wis. Expt. Station, bulletin 12 (see also under 203). 



Introduction. 3 

full justice cannot be done to different patrons of cream- 
eiies where payments for cieam delivered are made on 
the basis of this test. 

3. In cheese factories, and since the introduction of 
the centrifugal cream separator, in separator creamer- 
ies, the problem of just payment for the milk furnished 
by different patrons was no less perplexing than in the 
ease of gathered-cream factories. By the pooling sys- 
tem generally adopted, each patron received payment 
in proportion to the number of pounds of milk deliv- 
ered, irrespective of its quality. Patrons delivering rich 
milk naturally will not be satisfied with this system 
when they find that their milk is richer than that of 
their neighbors. The temptation to fraudulently in- 
crease the amount of milk delivered by watering, or to 
lower its quality by skimming, will furthermore prove 
too strong for some patrons ; the fact that it was diffi- 
cult to prove any fraud committed, from lack of a re- 
liable and practical method of milk analysis, rendered 
this pooling system still more objectionable. 

4. Formerly private dairymen and breeders of dairy 
cattle who desired to ascertain the butter-producing ca- 
pacities of the individual cows in their herds were 
obliged to do this by the cumbersome method of trial 
churnings : by saving the milk of each cow to be tested, 
for a day or a week, and churning separately the cream 
obtained. This requires a large amount of work when 
a number of cows are to be tested, and can not therefore 
be dene except with cows of great excellence or by farm- 
ers having plenty of hired help. Here again the need of 
a practical milk test was strongly felt. 



4 Testing Milk and Its Products. 

5. Introduction of milk tests. The first method 
which fulfilled all reasonable demands of a practical 
and reliable milk and cream test was the Babcock test, 
invented by Dr. S. M. Babcock, of the Wisconsin agri- 
cultural experiment station. A description of the test 
was first published in July, 1890, as bulletin No. 24 of 
that Station, entitled : A new method for the estimation 
of fat in milk, especially adapted to creamenes and 
cheese factories. This test, which is now known in all 
parts of the world where dairying is an important in- 
dustry, was not, however, the first method proposed for 
this purpose which could be successfully operated out- 
side of chemical laboratories. It was preceded by a num- 
ber of different methods, the first one published in this 
country being Short's method, invented by the late F. 
G. Short, and described in bulletin No. 16 of Wisconsin 
experiment station (July 1888). 

6. Short's test. In this ingenious method, a certain quan- 
tity of milk (20 cc.^) was boiled with an alkali solution and 
afterwards with a mixture of sulfuric and acetic acids; a layer 
of insoluble fatty acids separated on top of the liquid and was 
brought into the graduated neck of the test bottles by addition 
of hot water; the reading gave the per cent, of fat in the sam- 
ple of milk tested. 

Short's method did not find very wide application, both be- 
cause it was rather lengthy and its manipulations somewhat dif- 
ficult for non-chemists, and because several other methods were 
published shortly after it had been given to the public. 

7. Other milk tests. Of these may be mentioned, besides 
the Babcock test already spoken of, the Failyer and Willard 
method,^ Parsons' method,^ Cochran's test,* the Patrick or Iowa 

1 See 48, footnote. 

2 Kansas experiment station report, 1888, p. 149. 
* N. H. experiment station report, 1888, p. 69. 
STpurnal of Anal. Chem., Ill (1889), p. 381. 



Introduction. 5 

station test/ and the Beimling (Leffmann and Beam) test.'^ Of 
foreign methods published at about the same time, or previously, 
the Lactocrite/ Liebermann's method/ the Schmid/ Thorner/ 
Nahm/ Rose-Gottlieb/ sin-acid method/ and the Gerber sal- 
method^" may be noted. 

8. All these tests were similar in principle, the solids 
not fat of the milk being in all cases dissolved by the 
action of one or more chemicals, and the fat either 
measured as such in a narrow graduated tube, or 
brought into solution with ether, gasoline, etc., and a 
portion thereof weighed on evaporation of the solvent. 
While this principle is an old one, having been em- 
ployed in chemical laboratories for generations, its 
adaptation to practical conditions, and the details as 
to apparatus and chemicals used were, of course, new 
and different in each case. The American tests given 
were adopted to a limited extent within the states in 
which they originated and even outside of them, as in 
the case of the Short, Patrick and Beimling methods. 
The Babcock test, however, soon replaced the different 
methods mentioned, and during the past twenty years 
it has now been in almost exclusive use in creamer- 
ies and cheese factories in this country, where payments 
are made on the basis of the quality of the milk deliv- 



1 la. exp. sta., bull. No. 8, Feb. 1890 ; Iowa Homestead, June 14, 1889. 

2 Vermont exp. sta., bull. No. 21, September, 1890. For description 
of those and other volumetric methods of milk analysis, see Wiley, Agri- 
cultural Analysis, Vol. Ill, p. 490 et seq. ; Wing, Milk and its Products, 
p. 33 et seq., and Snyder, Chemistry of Dairying, pp. 112-113. 

3 Analyst, 1887, p. G. 
*Fresenius' Zeitschr., 22, 383. 
« Ibid., 27, 464. 

oChem. Centralbl., 1892, 429. 

7 Milch-Zeitung, 1894, No. 35 ; 1897, No. 50. 

8 Landw. Vers. Stat., 40, 1. 

9 Milch-Zeitung, 1904, No. 27. 
"Milch-Zeitung, 1906, No. 8. 



6 Testing Milk and Its Products. 

ered, as well as in the routine work in experiment sta- 
tion laboratories, and among milk inspectors and pri- 
vate dairymen. 

9. The Babcock test. The main cause why the 
Babcock test has replaced all competitors is doubtless 
to be sought, in its simplicity and its cheapness. It has 
but few manipulations, is easily learned, and is cheap, 
both in first cost and as regards running expenses. 

The test is furthermore speedy, accurate,^ and easily 
applied under practical conditions, and may therefore 
safely be considered the best milk test available at the 
present time. 

The method is applicable not only to whole milk, but 
to cream, skim milk, butter milk, whey, condensed milk, 
and (if a small scale for weighing out the sample is 
available) to cheese and butter.^ 

With all its advantages, the Babcock milk test is not 
in every respect an ideal test. The handling of the 
very corrosive sulfuric acid requires constant care and 
attention; the speed of the tester, the strength of the 
acid, the temperature of the milk to be tested, and other 
points, require constant watching, lest the results ob- 
tained be too low or otherwise unsatisfactory. In the 
hands of careful operators the test can, however, al- 
ways be relied upon to give most satisfactory results. 

10. Foreign methods. In European countries five 
practical milk and cream tests, besides the BabcocK lest, 



^ For a summary of comparative analyses made by the Babcock test 
and gravimetric analysis up to 1892, see Hoard's Dairyman, Oct. 7, 1892, 
p. 2560 ; also Schrott-Fiechtl, Milchzeitung, 1896, p. 183 et seq. 

2 The Babcock test, like the ether-extraction method gives, however, 
somewhat too low results in the case of skim milk (97). 



Introduction. 



are in use at the present time, viz. : Gerher's acid- 
butyrometer, the sin-acid (or no-acid) test, the lactocrite, 
De Laval's hutyrometer, and Fjord's centrifugal cream 
test} 

Of these tests the last 
one has never, to our 
knowledge, been intro- 
duced into this country, 
and the first four only tu 
a limited extent. 




^ '■ 



-f i_ vj_ I 




Fig. 1. The Gorbcr acid- 
butyrometer. 



11. The Gerber method 

(fig. 1) is essentially the old 
Beimling method (7), worked 
out independently by the 
Swiss chemist, Dr. N. Gerber. 
In this test sulfuric acid of 
the same strength as in the 
Babcoek test is used, and a 
small quantity of amyl alco- 
hol is added. The amyl alcohol facilitates the separation of the 
fat, but may introduce a source of error on account of impuri- 
ties contained therein, when the results obtained with a new lot of 
alcohol can not be checked against gravimetric analysis or against 
tests made with amyl alcohol known to give correct results. This 
method is, however, extensively used in European countries, hav- 
ing there practically replaced the Babcoek test or been adopted 
in preference to it. 

11a. The sin-acid test was invented by the German chemist 
A, Sichler and published in 1904.^ In place of the sulfuric acid 
used in the Babcoek and Gerber tests, Sichler employs a solution of 

1 The Lisfer-Ba'bcock milk test advertised in English papers and 
known as such in England, is the regular Babcoek test, to which the 
English manufacturers have affixed their name ; the same applies to the 
Ahlhorn-Babcock and the Knigmann-Bahcock methods. 

2 Gerber, Die praktische Milchpriifung, 7th edition, 1900. 

^ Milchztg., 1904, p. 417. The word sin (sine) is Latin and means 
without; hence, when introduced into this country in 1909 the method 
was called the no-acid test. 



8 



Testing Milk and Its Products. 



Rochelle salts, sodium sulfate and sodium hydroxid.^ 150 cc. of this 
mixture of salts are dissolved in 1 liter of water. In testing milk, 
11 cc. of this solution and 0.6 cc. of '^sinol" (isobutylalcohol) are 
added to 10 cc. of milk. After thorough mixing of the milk and 
solution the test bottles are placed in water of 113° F. for 3-5 
minutes, when they are shaken till all the curd dissolves. They 
are then revolved in a centrifuge for 3 minutes and the results read 
off. By heating the bottles for 1 hour in boiling hot water correct 
results may be obtained without the use of a centrifuge. The 
main advantages of the method appear to lie in this fact and in 
that the use of a corrosive acid is avoided. 

12. The Lactocrite was one of the earliest practical milk 
tests introduced. It was invented by De Laval in 1886. The 
acids used in this test are lactic acid (originally, acetic acid) 
with a mixture of hydrochloric and sulfuric acids. This test is 
now but rarely met with. 




Fig. 2. De Laval's butyrometer. 

13. In the De Laval butyrometer (fig. 2) the same acid is 
used as in the Babcock test, but the tubes employed and the 
manipulations of the method differ materially from this test; a 
smaller sample of milk is taken (only 2 cc.) and a correspond- 
ingly small quantity of acid used. Where a large number of 

1 Barthel-Goodwin, Methods used in Examination of Milk and Dairy 
Products, p. 77. 



Introduction. 



milk samples are tested every day, as, for instance, in milk control 
stations, the butyrometer may be preferable to the Babcock test; 
but it requires more skill of the operator and does not work satis- 
factorily in case of sour, loppered, or partially churned milk. 

14. Fjord's centrifugal cream tester' (fig. 3) is exten- 
sively used m Denmark and is mentioned in this connection as it 
furnishes, as a rule, a reliable method for comparing the qual- 
ity of different lots of milk. The method was published in 1878, 
by the late N. J. Fjord, director of the state experiment station 
in Copenhagen, through whose exertions and on whose authority 
it was introduced into Danish creameries in the middle of the 
eighties. No chemicals are added in this test, the milk being 
simply placed in glass tubes, seven inches long and about two 
thirds of an inch in diameter, and whirled for twenty minutes 
at a rate of 2000 revolutions per minute at 55°C (131°F.). 
The reading of the cream layer thus obtained gives the per cent 
of cream, and not of butter 
fat, in the sample tested. One 
hundred and ninety-two sam- 
ples of milk can be tested 
simultaneously. Within the 
limits of normal Danish herd 
milk, the results obtained cor 
respond to the per cents of fat 
present in the samples, one per 
cent, of cream being equal to 
about 0.7 per cent, of fat; 
outside of these limits the test 
is, however, unreliable, especially in case of very rich milk and 
strippers' milk. Only sweet milk can be tested by this method. 
Milk tests proper, like the Gerber, Babcock and De Laval tests, 
have during recent years been introduced into Denmark and 
are used in some creameries.^ 

^ State Danish experiment station, Copenhagen, sixth and nintb re- 
ports, 1885-7. 

2 Among foreign milk tests in use abroad should also be mentioned 
the Lindstrom 'butyrometer and the Wollny rcfractometer, both of 
which, in the hands of trained chemists, may prove better adapted for 
use where a very large number of samples are to be tested af a time, 
than any other available milk test. 




Fig. 3. 



Fjord s centrifugal cream 
tester. 



CHAPTER I. 
COMPOSITION OF MILK AND ITS PRODUCTS. 

Before taking up the discussion of the Babcock milk 
test, a brief description of the chemistry of milk and its 
products is given, so that the student may understand 
what are the components of dairy products, and the re- 
lation of these to each other. Only such points as have 
a direct bearing upon the subject of milk testing and 
the use of milk tests in butter and cheese factories or 
private dairies will be treated in this chapter, and the 
reader is referred to standard works on dairying for 
more detailed information in regard to the composition 
of dairy products. 

15. Composition of milk. Milk is composed of the 
following substances: water, fat, casein, albumen, milk 
sugar, and ash. A few other substances are present in 
small quantities, but they are hardly of sufficient prac- 
tical importance to be considered here. The com- 
ponents of the milk less the water are known collect- 
ively as milk solids or total solids, and the total solids 
less the fat, i. e., casein, albumen, milk sugar, and ash, 
are often spoken of as solids not fat or the non-fatty 
milk solids. The milk serum includes all components 
vjf the milk less the fat; the serum solids are therefore 
another name for the solids not fat; when given, they 
are, however, generally calculated to per cent, of milk 
serum, not of milk. If, e. g., a sample of milk contains 



Composition of Milk and Its Products. 11 

nine per cent, of solids not fat, and three per cent, of 
fat, the milk serum will make up 97 per cent, of the 

milk, and the serum solids, ^)^ = 9-28 per cent, of 

the milk serum. 

i6. Water. The amount of water contained in cow's 
milk ranges from 82 to 90 per cent. Normal cow's milk 
will not, as a rule, contain more than 88 per cent, of 
water, nor less than 84 per cent. In states where there 
are laws regulating the sale of milk, as is the -case in 
twenty-two states of the Union (see Appendix, Table 
II), the maximum limit for Avater in milk in all instances 
but one (South Carolina) is 8^8 per cent.; the state men- 
tioned allows 88.5 per cent, of water in milk offered 
for sale within her borders. The effect of fraudulently 
increasing the water content of milk by watering is con- 
sidered under Adulteration of Milk (121). 

17. Fat. The fat in milk is not in solution, but sus- 
pended as very minute globules, Avhich form an emul- 
sion with the milk serum; the globules are present in 
immense numbers, viz., on the average about one hun- 
dred millions in a single drop of milk ; a quart of milk 
will contain about two thousand billions of fat globules, 
a number written with thirteen figures. The sizes of 
the globules in the milk from the same cows vary ac- 
cording to the stage of the period of lactation, the glob- 
ules being largest at the beginning of the lactation 
period, and gradually decreasing in size with its prog- 
ress. Different breeds of cows have fat globules of 
different average sizes; the Channel Island cows are 
thus noted for the relatively large fat globules of their 



12 Testing Milk and Its Products. 

milk, while the lowland breeds, the Ayrshire, and other 
breeds have uniformly smaller globules. The diameter 
of average sized fat globules in fresh milkers is about 
.004 millimeter, or one six-thousandth of an inch; that 
is, it takes about six thousand such globules placed side 
by side to cover one inch in length. The globules of 
any sample of milk vary greatly in size; the largest 
globules are recovered in the cream when the milk is 
set or run through a cream separator, and the smallest 
ones remain in the skim milk; thoroughly skimmed sep- 
arator skim milk contains only a small number of very 
minute fat globules. 

Milk fat is composed of so-called glycerides of the 
fatty acids, i. e., compounds of the latter with glycerin; 
some of the fatty acids are insoluble in water, viz., 
palmitic, stearic, and oleic acids, while others are solu- 
ble and volatile, the chief ones among the latter being 
butyric, caprylic, and capronic acids. The glycerides 
of the insoluble fatty acids make up about 92 per cent, 
of the pure milk fat; about 8 per cent, of the glycer- 
ides of volatile fatty acids are therefore found in nat- 
ural milk- (and butter-) fat. The distinction between 
natural and artificial butter lies mainly in this point, 
since artificial butter (butterine, oleomargarine) as well 
as other solid animal fats contain only a very small 
quantity of volatile fatty acids. The glycerides of the 
volatile fatty acids are unstable compounds, and are 
easily decomposed through the action of bacteria or 
light; the volatile fatty acids thus set free, principally 
butyric acid, are the cause of the unpleasant odor met 
with in rancid butter. 



Composition of Milk and Its Products. 13 

Cow's milk generally contains between three and six 
per cent, of fat; in American milk we find, on the 
average, toward four per cent, of fat. The milk from 
single cows in perfect health will occasionally go below 
or above the limits given, but mixed herd milk rarely 
falls outside of these limits. The standard adopted by 
the U. S. government for fat in milk is 3.25 per ct. 
The legal standard for fat in milk in most states of the 
Union is 3 per cent. ; Rhode Island allows milk contain- 
ing 2.5 per cent, of fat to be sold as pure, while Georgia 
and Minnesota require it to contain 3.5 per cent., and 
Massachusetts 3.7 per cent, (in the months of May and 
June; see Appendix, Table II). 

i8. Casein and albumen. These belong to the so- 
called nitrogenous substances, distinguished from the 
other components of the milk by the fact that they con- 
tain the element nitrogen. Another name is alhiimin- 
oids or protein compounds. Casein is precipitated by 
rennet in the presence of soluble calcium salts, and by 
dilute acids and certain chemicals ; albumen is not acted 
upon by these agents, but is coagulated by heat, a tem- 
perature of 170° F. being sufficient to effect a perfect 
coagulation. The casein, fat, and water, are the main 
components of nearly all kinds of cheese. In the manu- 
facture of Cheddar and most other solid cheeses, the 
casein is coagulated by rennet, and the curd thus 
formed holds fat and whey mechanically, the latter 
containing in solution small quantities of non-fatty 
milk solids. The albumen goes into the whey and is 
lost for cheese making ; in some countries it is also made 
into cheese by evaporating the whey under constant 



X4: Testing Milk and Its Products. 

stirring; whole milk of cows or goats is often added and 
incorporated into such cheese (primost, gjetost). 

Casein is present in milk partly in solution, in the 
same way as milk sugar, soluble ash-materials and albu- 
men, and partly in suspension, in an extremely fine col- 
loidal ccJndition, mixed or combined with insoluble cal- 
cium phosphates. The casein and calcium phosphates 
in suspension in milk may be retained on a filter made 
of porous clay (so-called Cham'berland filters). 

About 80 per cent, of the nitrogenous compounds of 
normal cow's milk are made up of casein; the rest is 
largely albumen. If the amount of casein in milk be 
determined by precipitation with rennet or dilute acids, 
and the albumen by boiling the filtrate from the casein 
precipitate, it will be found that the sum of these two 
compounds do not make up the total quantity of nitro- 
genous constituents in the milk. The small remaining 
portion (about five per cent, of the total nitrogenous 
constituents) has been called by various authors, globu- 
lin, albumose, hemi-albumose, nuclein, nucleon, proteose, 
etc. The nitrogenous constituents of milk are very un- 
stable compounds, and their study presents many and 
great difficulties; as a result we find that no two scien- 
tists who have made a special study of these compounds 
agree as to their properties, aside from those of casein 
and albumen, or their relation to the nitrogenous sub- 
stances found elsewhere in the animal body. For our 
purpose we may, however, consider the nitrogen com- 
pounds of milk as made up of casein and albumen, and 
the term casein and albumen, as used in this book, is 
meant to include the total nitroo^enous constituents of 



Composition of Milk and Its Products. 15 

milk, obtained by multiplying the total nitrogen eon- 
tent of the milk by 6.25.^ 

The quantity of casein in normal cow's milk will vary 
from 2 to 4 per cent., and of albumen, from .5 to .8 per 
cent. The total content of casein and albumen ranges 
between 2.5 and 4.6 per cent, the average being about 
3.2 per cent. Milk with a low fat content will contain 
more casein and albumen than fat, while the reverse is 
generally true in case of milk containing more than 3.5 
per cent, of fat. 

19. Milk sugar or lactose belongs to the group of 
organic compounds known as car-hohydrates. It is a 
commercial product manufactured from whey and is 
obtained in this process as pale white crystals, of less 
sweet taste and less soluble in water than ordinary 
sugar (cane sugar, sucrose). About 70 per cent, of the 
solids in the whey, and 33 per cent, of the milk solids, 
are composed of milk sugar. 

When milk is left standing for some time, viz., from 
one to several days, according to its cleanliness and 
the temperature of the surrounding medium, it will 
turn sour and soon become thick and loppered. This 
change in the composition and appearance of the milk 
is brought about through the action of acid-forming 
bacteria on the milk-sugar. These are present in ordi- 
nary milk in immense numbers, and under favorable 
conditions of temperature multiply rapidly, feeding on 



^ The factox' 6.25 is generally used for obtaining the casein and albu- 
men from the total nitrogen in the milk, on the theory that protein 
compounds contain 16% N. ; the factor 6.37 would, however, be more 
correct, since casein and albumen, according to our best authorities, 
contain on the average 15.7 per cent of nitrogen (^^ 4^^ =6.37) 



16 Testing MUk and Its Products. 

the milk sugar as they grow, and decomposing it into 
lactic acid. When this change alone occurs, there is 
not necessarily a loss in the nutritive value of the milk, 
since milk sugar breaks up directly into lactic acid. 
This is shown by ihe following chemical formula : 

C12H22O11H2O (lactose) =4 CgHgOs {lactic acid)} 

Ordinarily the souring of milk is, however, more 
complicated, and other organic bodies, like butyric acid, 
alcohol, etc., and gases like carbonic acid are formed, 
resulting in a loss in the feeding value of the milk. 
While sour milk may therefore contain a somewhat 
smaller proportion of food elements than sweet milk, 
it will generally produce better results when fed to 
farm animals, especially pigs, than is obtained in feed- 
ing similar milk in a sweet condition. The cause of this 
may lie in the stimulating effect of the lactic acid of 
sour milk on the appetites of the animals, or in its aid- 
ing digestion by increasing the acidity of the stomach 
juices. 

That the souring of milk is due to the activities of 
bacteria present therein is shown clearly by the fact 
that sterile milk, i. e., milk in which all germ life has 
been killed, will remain sweet for any length of time 
when kept free from infection. 

The amount of milk sugar found in normal cow's 
milk varies from 3.5 to 6 per cent., the average content 
being about 5 per cent. ; in sour milk this content is 
decreased to toward 4 per cent. 

1 One molecule of milk sugar is composed of 12 atoms of carbon (C), 
22 atoms of hydrogen (H), 11 atoms of oxygen (O), and one molecule 
of water (H^Q). In the same way, the lactic acid molecule consists of 3 
atoms of carbon, 6 atoms of hydrogen, and 3 atoms of oxygen. 



Composition of Milk and Its Products. 17 

20. Ash. The ash or mineral substances of milk are 
largely composed of chlorids and phosphates of sodium, 
potassium, magnesium and calcium; iron oxid and sul- 
furic and other acids are also present in small quanti- 
ties among the normal mineral milk components. The 
amounts of the different bases and acids found in milk 
ash have been determined by a number of chemists ; the 
average figures obtained are given in the following 
table, calculated per 100 parts of milk (containing .75 
per cent, of ash) and per 100 parts of milk ash. 

Mineral Components of MilTc. 

In per cent of milk. In per cent of ash 

Potassium oxid (KjO) .19 per ct. 25.64 per ct. 

Sodium oxid (^Na^O) .09 12.45 

Lime (CaO) .18 24.58 

Magnesia (MgO; .02 3.09 

Iron oxid (Fe^Oa) .002 .34 

Phosphoric anhydrid (P2O5)-— .16 21.24 

Chlorin (01) .12 16.34 

.762 per ct. 103.68 per ct. 

Less oxygen, corresponding to 

chlorin .012 3.68 

.75 100.00 

The combinations in which the preceding bases and 
acids are contained in the milk are not known with cer- 
tainty. According to Soldner, 36 to 56 per cent, of the 
phosphoric acid found in milk, and from 53 to 72 per 
cent, of the lime, are present in suspension in the milk 
as di- and tri-calcium phosphates, and may be filtered 
out by means of Chamberland filters (18), or by long 
continued centrifuging (Babcock^). The rest of the 
ash constituents are dissolved in the milk serum. 

* Wisconsin experiment station report 12, p. 93. 



18 Testing Milk and Its Products. 

The ash content of normal cow's milk varies but lit- 
tle, as the rule only between .6 and .8 per cent., with an 
average of .7 per cent. Milk with a high fat content 
generally contains about .8 per cent, of ash; strippers' 
milk always has a high ash content, at times even ex- 
ceeding one per cent. Ordinarily, the mineral constitu- 
ents are least liable to variations of any of the com- 
ponents of the milk. 

21. Other components. Besides the milk constitu- 
ents enumerated and described in the preceding pages, 
normal milk contains a number of substances which are 
present in but small quantities and have only scientific 
interest, such as the milk gases (carbonic acid, oxygen, 
nitrogen), citric acid, lecithin, cholesterin, urea, hypo- 
xanthin, lactochrome, etc. 

22. Average composition. The average percentage 
composition of cow's milk will be seen from Table I in 
the Appendix. The following statement shows the lim- 
its within which the components of normal American 
cows' milk are likely to come: 

Minimum. Maximum. Average. 

Water 82.0 per ct. 90.0 per ct. 87.4 per ct. 

Fat 2.3 7.8 3.7 

Casein and albumen 2.5 4.6 3.2 

Milk sugar 3.5 6.0 5.0 

Ash .6 .9 .7 

23. Colostrum milk. The liquid secreted directly 
after parturition is known as colostrum milk or biest- 
ings. It is a thick, yellowish, viscous liquid; its high 
contents of albumen and ash are characteristic, and also 
its low content of milk sugar. Owing to the large quan- 
tity of albumen which colostrum contains, it will coagu- 



Composition of Milk and Its Products. 19 

late on being heated toward the boilino- point. In the 
course of three or four days the secretion of the udder 
gradually changes from colostrum to normal milk; the 
milk is considered fit for direct consumption or for the 
manufacture of cheese and butter, when it does not co- 
agulate on boiling and is of normal appearance as re- 
gards color, taste, and other properties. For composi- 
tion of colostrum milk, see Appendix, Table I. 

24. Composition of milk products. In addition to 
its use for direct consumption, milk is the raw-material 
from which cream, butter, cheese, and condensed milk 
are obtained. 

When milk is left standing for some time or subjected 
to centrifugal force, it will separate into two distinct 
parts, cream and skim milk. The proportion of each 
part which is obtained, and their chemical composition, 
will depend on the method by which the separation is 
effected; in the so-called gravity process where the 
cream is separated on standing— either in shallow pans 
in the air, 01 in deep cans, submerged in cold water— a 
less complete separation is reached, since the skim milk 
obtained is richer in fat than when the separation takes 
place through the action of centrifugal force. 

In modern creameries the milk is now always skimmed 
by means of cream separators. Separator cream will 
contain from 15 to 50 per cent, of fat, according to the 
adjustment of the separator and of the milk supply; 
ordinarily it contains about 25 per cent, of fat. Cream 
of average quality, in addition to the fat content given, 
consists of about 66 per cent, of water, 3.8 per cent. 



20 Testing Milk and Its Products. 

casein and albumen, 4.3 per cent, milk sugar, and .5 per 
cent. ash. 

The skim milk is made up of the milk serum (15) and 
a small amount of fat, viz., toward .4 per cent, when 
obtained by the gravity process, and less than .2 per 
cent, in the case of separator skim milk. Milk set in 
shallow pans in the air, or in deep cans in water above 
60° F., will give skim milk containing one-half to over 
one per cent, of fat. Skim milk is used as a food for 
young farm animals or as human food, and in this 
country only in exceptional cases, for the manufacture 
of cheese. 

25. Cream is used for the manufacture of butter or 
for direct consumption. In the former case a certain 
amount of acidity is generally allowed to develop there- 
in previous to the churning process. This secures a 
more complete churning and produces peculiar flavors 
in the butter, without which it would seem insipid to 
most people. Nearly all butter made in this coun 
try is salted before being placed on the market 
Salt is a preservative and for a limited length of 
time prevents butter from spoiling. Unsalted butter 
made from sweet cream is a common food article in 
Southern and Middle Europe, but only an insignificant 
amount is manufactured and consumed in America; 
salted butter made in Europe also contains considerably 
less salt than American butter (see Appendix, Table I) . 
Butter contains all the fat of the cream except a small 
portion which goes into the butter milk, and a small 
unavoidable mechanical loss incident to the handling of 
the products. Butter should contain at least 80 per 



Composition of Milk and Its Products. 21 

cent, of fat and ordinarily contains about 83 per cent.; 
besides this amount of fat, butter is generally composed 
of about 13 per cent water, 1 per cent curd and lactic 
acid, and 3 per cent salt. 

Butter milk has a composition similar to skim milk, 
but varies much more than this product, according to 
the acidity, temperature, and thickness of the cream, 
and other churning factors. It contains about 9 per 
cent, of solids, viz., milk sugar (and lactic acid) 4 per 
cent, casein and albumen 4 per cent., fat .3 per cent., 
and ash .7 per cent. 

26. The quantities of butter and by-products obtained 
in the manufacture of butter are as follows: 1000 lbs. 
of milk of average quality will give about 850 lbs. of 
skim milk and 145 lbs. of cream (separator slime and 
mechanical loss, 5 lbs.) ; this amount of cream will make 
about 42 lbs. of butter and 100 lbs. of butter milk (me- 
chanical loss, 3 lbs.). 

27. In the manufacture of American cheddar cheese, 
whole milk is heated to about 86° F., and a small amount 
of rennet extract is added, which coagulates the casein; 
the albumen of the milk is not precipitated by rennet 
and remains in solution (18). *' Green" cheese, as taken 
from the press, is made up, roughly speaking, of 37 per 
cent, of water, 34 per cent, of fat, 24 per cent, of albu- 
minoids (nearly all casein), and about 5 per cent, of 
milk sugar, lactic acid, and ash (largely salt). In the 
curing of cheese there is some loss by drying, but the 
main changes occur in the breaking up of the firm curd 
into soluble and digestible nitrogenous compounds, pep- 
tones, amids, etc. 



22 Testing Milk and Its Products. 

Whey is the by-product obtained in the manufacture 
of cheese. It consists of water and less than 7 per cent, 
of solids ; of the latter about 5 per cent, is milk sugar, 
.8 per cent, albumen, .6 per cent, ash, and .3 per cent, 
fat. Whey is generally used for feeding farm animals; 
it is the raw-material from which milk sugar and whey 
cheese are made. 

28. Condensed milk is manufactured from whole milk 
or from partially skimmed milk. In many brands a 
large quantity of sugar (25 per cent, or more) is added 
to the condensed milk in the process of manufacture so 
as to secure perfect keeping quality in the product. 
Brands to which no sugar has been added are also on 
the market, and in case of such brands the relation be- 
tween the various solid constituents of the condensed 
milk will be essentially the same as that between the 
constituents of milk solids. Condensed milk should con- 
tain at least 7.7% fat, and must be free from preserva- 
tives and other foreign substances (except sugar). 

Tables are given in the Appendix showing the aver- 
age composition of the various milk products. 

Questions. 

1. What is the average composition of cow's milk; state briefly 
the properties of the various constituents. 

2. What is meant by total solids; solids not fat; milk serum; 
serum solids? 

3. What is colostrum milk? Give its average composition, and 
in what particulars it mainly differs from normal milk. 

4. Give the average composition of cream, skim milk, butter- 
milk, whey, butter and cheddar cheese. 

5. Explain the distribution of the components of milk in (a) 
butter-making, (b) cheese-making. 



CHAPTER II. 
SAMPLING MILK. 

29. The butter fat in milk is not in solution, like 
sugar dissolved in water, but the minute fat globules or 
drops, in which form it occurs, are held in suspension 
in the milk serum (17). Being lighter than the serum, 
the fat globules have a tendency to rise to the surface 
of the milk. If, therefore, a sample of milk is left 
standing for even a short time, the upper layer will 
contain more fat than the lower portion. This fact 
should always be borne in mind when milk is sampled. 
The rapidity with which fat rises in milk can be easily 
demonstrated by allowing a quantity of sweet milk to 
stand in a cylinder or a milk can for a few minutes, 
and testing separately the top, middle and bottom layer 
of this milk. 

The amount of mixing necessary to evenly distribute 
the constituents of milk throughout its mass may be as- 
certained by adding a few drops of cheese color to a 
quart of milk. The yellow streaks through the milk 
will be noticed until it has been poured several times 
from one vessel to another, when the milk will have a 
uniform pale yellow color. Stirring with a stick or a 
dipper will not produce an even mixture so quickly or 
so completely as pouring the milk a few times from one 
vessel to another. In sampling milk for testing it 
should always be mixed just before the milk is 
measured into the bottle ; if several tests are made of a 
sample, the milk should be mixed before each sampling. 



24 Testing Milk and Its Products. 

30. Partially churned milk. A second difficulty 
sometimes met with in sampling whole milk arises from 
the fact that a part of the butter fat may be separated 
in the form of small butter granules, by too zealous mix- 
ing or by reckless shaking in preparing the sample for 
testing. This will happen most readily in case of milk 
from fresh cows or of milk containing exceptionally 
large fat globules. When some of the butter granules 
are thus churned out, they quickly rise to the surface of 
the milk after pouring and cannot again be incorporated 
in the milk by simple mixing; it is, therefore impossi- 
ble to obtain a fair sample of such milk for testing 
without taking special precautions which will be ex- 
plained in the following. The granules of butter may 
be so small as to pass into the pipette with the milk and 
the quantity measured thus contain a fair proportion 
of them, but they will be found sticking to the inside 
of the pipette when this is emptied, and thus fail to be 
carried into the test bottle with the milk. 

A similar partial churning of the milk will sometimes 
take place in the transportation cans. When such milk 
is received at the factory, the butter granules are caught 
by the strainer cloth through which the milk is poured, 
and are thus lost both to the factory and to the farmer. 
This separated fat cannot be added to the cream or to 
the granular butter, without running the risk of mak- 
ing mottled butter, and it will not enter into the sam- 
ple of milk taken for testing purposes. 

When milk samples are sent by mail or express in 
small bottles, or carried to the place of testing, they 
often arrive with lumps of butter floating in the milk 
or sticking to the glass. This churning of the milk can 



Sampling Milk. 25 

be easily prevented by completely filling the bottle or 
the can. If there is no space left for the milk in which to 
splash around, the fat will not be churned out in transit. 
31. Approximately accurate results may generally be 
obtained with a partially churned sample of milk, if a 
teaspoonful of ether be added to it. After adding the 
ether, cork the bottle and shake it until the lumps of 
butter are dissolved. This ether solution of the butter 
will mix with the milk and from the mixture a fairly 
satisfactory sample may generally be taken. The dilu- 
tion of milk by the ether introduces an error in the 
testing, and only the smallest quantity of ether neces- 
sary to dissolve the lumps of butter should be used. If 
desired, a definite quantity of ether, say five per cent, 
of the volume of the sample of milk to be tested, may 
be added; in such cases the result of the test must be 
increased by the per cent, of ether added. 

Example. — To a 4-oz. sample (120 cc.) of partially churned 
milk, 5 per cent., or 6 cc. of common ether are added; the mix- 
ture gave an average test of 4.2 per cent. The test must be in- 
creased by ^ -j ^^X4.2=.21 per cent., and the original milk there- 
fore contained. 4.2 -{-.21=4.41 per cent, of fat. 

Milk containing ether must be mixed cautiously with 
acid in making a test, so as to avoid a loss of the contents 
of the bottle by the sudden boiling of the ether due to 
the heat evolved in mixing the milk and the acid. 

Instead of adding ether to partially churned sam- 
ples, the milk may be heated t6 about 110° F. for a 
few minutes, so as to melt the butter granules; the 
sample is now shaken vigorously until a uniform mix- 
ture of milk and melted butter is obtained, and a pi- 
petteful is then quickly drawn from the sample. 



26 Testing Milk and Its Products. 

32. Sampling sour milk. When milk becomes sour, 
the casein is coagulated and the mechanical condition of 
the milk thereby changed so as to render difficult a cor- 
rect sampling. The butter fat is not, however, changed 
in the process of souring; this has been shown by one 
of us, among others, in a series of tests which were 
measured from one sample of sweet milk into six test 
bottles. A test of the milk in one of these test bottles 
was made every month for six months, and approxi- 
mately the same amount of fat was obtained in the 
tests throughout the series, as was found originally in 
the milk when tested in a sweet condition.^ If the milk 
is in condition to be sampled, souring does not there- 
fore interfere with its being tested by the Babcock test 
or with the accuracy of the results obtained. 

In order to facilitate the sampling of sour or lop- 
pered milk, some chemical may be added which will re- 
dissolve the coagulated casein and produce a uniform 
mixture that can be readily measured with a pipette. 
Any alkali (powdered potash or soda, or liquid ammo- 
nia) will produce this effect. Only a very small quan- 
tity of powdered alkali is necessary for this purpose. 
The complete action of the alkali on sour milk requires 
a little time, and the operator should not try to hasten 
the solution by adding too much alkali. An excess of 
alkali will often cause such a violent action of the sul- 
furic acid on the milk to which the acid is added (on 
account of the heat generated or the presence of car- 

1 See Hoard's Dairyman, April 8, 1892. The same holds true for 
cream, as shown by Winton (U. S. Dept. Agr., Div. of Chemistry, bull. 
43, p. 112). As to length of time Babcock tests will keep, see Vt. 
exp. sta., bull. 106. 



Testing Milk and Its Products, 27 

bonates in the alkali) that the mixture will be thrown 
out of the neck of the test bottle when this is shaken in 
mixing the milk and the acid (37). When powdered 
alkali is added to the milk, it should be allowed to 
stand for a while, with frequent shaking, until the curd 
is all dissolved and an even translucent liquid is ob- 
tained. Such milk may become dark-colored by the ac- 
tion of the alkali, but this color does not interfere witb 
the accuracy of the test. 

Instead of powdered soda or potash, these substances 
dissolved in water (soda or potash lye), or strong am- 
monia, may be used for the purpose of dissolving the 
coagulated casein in sour milk. In this case, a definite 
proportion of alkali solution must be taken, however, 5 
per cent, of the volume of milk being usually sufficient, 
and the results obtained are increased accordingly. 

33. Sampling frozen milk. When milk freezes, it 
separates into two distinct portions : Milk crystals, 
largely made up of water, with a small admixture of fat 
and other solids, and a liquid portion, containing nearly 
all the solids of the milk. In sampling frozen milk it 
is therefore essential that the liquid and the frozen part 
be warmed and thoroughly mixed by pouring gently 
back and forth from one vessel into another; the sam- 
ple is then taken and the test proceeded with in the 
ordinary manner (36). 

Questions. 

1. What precautions must be taken in sampling milk? Give 
reasons. 

2." How can a fair sample be taken of (a) partially churned 
milk, (b) sour milk, (c) frozen milk? 

3. If 15 cc. of ammonia are added to 500 cc. of sour milk, 
and a test of 3.45 obtained, what is the correct test of the milk? 



CHAPTER III. 



THE BABCOCK TEST. 



34. The Babcock test is based on the fact that strong 
sulfuric acid will dissolve all non-fatty solid constitu- 
ents of milk and 
other dairy products, 
and thus enable the 
fat to separate on 
standing. To effect a 
speedy and complete 
separation of the fat, 
the bottles holding 
the mixture of milk 
and acid are placed 
in a centrifugal ma- 
chine, a so-called 
tester, and whirled 
for four minutes ; hot 
water is then added 
so as to bring the 
liquid fat into the 
graduated neck of 
the test bottles, and 
after a repeated 

Fig. 4. The first Babcock tester made. i • t .^ , ,, 

whirling, the length 
of the column of fat is read off, showing the per cent, 
of fat contained in the sample tested. 




The Bahcock Test. 29 

Sulfuric acid is preferable to other mineral acids for 
the purpose mentioned, on account of its affinity to 
water ; when mixed with milk, the mixture heats greatly, 
thus keeping the fat liquid without the application of 
artificial heat and rendering possible a distinct reading 
of the column of fat brought into the neck of the test 
bottles. 

So far as is known, any kind of milk can be tested 
by the Babcock test. Breed, period of lactation, qual- 
ity or age of the milk are of no importance in using this 
method, so long as a fair sample of milk can be secured. 
In cases of samples of milk or other dairy products 
rich in solids it requires a little more effort to obtain a 
thorough mixture with the acid than with dairy prod- 
ucts low in solids, like skim milk or whey, which may 
be readily mixed with the acid. 

A.— Directions for Making the Test. 

35. The various steps in the manipulation of the 
Babcock test are discussed in the following pages; at- 
tention is drawn to the difficulties which the beginner 
and others may encounter in the use of the test, and 
the necessary precautions to be observed in order to 
obtain accurate and satisfactory results are explained 
in detail. The effort has been to treat the subject ex- 
haustively and from a practical point of view, so that 
persons as yet unfamiliar with the test may turn to 
the pages of this book for help in difficulties which 
they may meet in their work in this line. 

36. Sampling. The sample to be tested is first mixed 
by pouring the milk from one vessel to another two or 



30 



Testing Milk and Its Products. 



three times, so that every portion thereof will 
contain a uniform amount of butter fat (29). 
The measuring pipette (fig. 6), which has a 
capacity of 17.6 cubic centimeters/ is filled witji 
the milk immediately after the 
mixing is completed, by suck- 
ing the milk into it until this 
rises a little above the mark 
around the stem of the pipette; 
the forefinger is then quickly 
placed over the end of the pi- 
pette before the milk runs down 
below the mark. By slightly 
releasing the pressure of the 
finger on the end of the pipette, 
the milk is now allowed to run 
down until it just reaches the 
mark on the stem; the quantity 
of milk contained in the pi- 
pette will then, if this is cor- 
rectly made, be exactly 17.6 cc. 
The finger should be fairly dry 
in measuring out the milk so 
that the delivery of milk may 
be readily checked by gentle 
pressure on the upper end of 
the pipette. 

The point of the pipette is 
now placed in the neck of a 

Fig. 5. Babcock milk 

test bottle. Babcock test bottle (fig. 5), 



^mm 



Fig. 6. 
17.6 cc. pi- 
pette. 



' See p. 45, foot note. 



The Bahcoch Test. 



31 





and the milk is allowed to flow slowly down the inside 
of the neck. Care must be taken that none of the milk 
measured out is lost in this transfer. The portion of 
the milk remaining in the point of the pipette is blown 
into the test bottle. 
The best and saf- 
est manner of hold- 
ing the bottle and the 
pipette in this trans- 
fer is shown in fig. 
7. Fig. 8 shows a 
position which should 
be avoided, since by 
holding the bottle in 

this way, there is ; danger that some of the 

milk may completely fill 
the neck of the bottle, 
and as a result, flow 
over the top of the neck. 
Pipettes, the lower 
part of which slip read- 
ily into the necks of the 
test bottles, may be 
emptied by lowering 
the pipette into the 
neck of the bottle till 
it rests on its rim, when 

Fig. 7. The right way of emptying the milk is allowcd to 
pipette into test bottle. . 

run into the test bottle. 
37. Adding acid. The acid cylinder (fig. 9) hold- 
ing 17.5 cc, is filled to the mark with sulfuric acid 01 



32 



Testing Milk and Its Products. 



a specific gravity of 1.82-1.83. This amount of acid is 

carefully poured into the test bottle containing the milk. 

In adding the acid, the test bottle is conveniently held 

at an angle (see fig. 7), so that the acid will run down 

the wall of the bottle and 

not run in a small stream into 

the center of the milk, the 

bottle being slowly turned 

around and the neck thus 

cleared of adhering milk. By 

pouring the acid into the 

middle of the test bottle, 

there is also a danger of com- 
pletely filling this with acid, 

in which case the plug of 

acid formed will be pushed 

over the edge of the neck by 

the expansion of the air in 

the bottle, and may be spilled 
on the hands of the operator. 
The milk and the acid in 
the test bottle should be in 
two distinct layers, without 
much of a black 
band of partially 
mixed liquids be- 
tween them. Such 
a dark layer is of- 
ten followed by an indistinct separation of the fat in 
the final reading. The cause of this may be that a par- 
tial mixture of acid and milk before the acid is diluted 




Fig. 8. 



The wrong way of emptying pipette 
into test bottle. 



The Babcock Test. 



33 




with the water of the milk will bring about too strong 
an action of the acid on this small portion of the milk, 
and thus char the fat contained therein. The appear- 
ance of black flocculent matter in or below the col- 
umn of fat which generally results, in 
either case renders a correct measurement 
difficult and at times even impossible; if 
the black specks occur in the fat column 
itself, the readings are apt to be too high ; 
if below it, the difficulty comes in decid- 
ing where the column of fat begins, 

S8, Mixing milk and acid. After add- 
ing the acid, this is carefully mixed with 
the milk by giving the test bottle a rotary 
motion. In doing this, care should be 

Fig. U. 17.5 cc. 

taken that the liquid is not shaken into acid cylinder, 
the neck of the test bottle. When once begun, the mix- 
ing should be continued until completed; a partial and 
interrupted mixing' of the liquids will often cause more 
or less black material to separate wdth the fat when the 
test is finished. Clots of curd which separate at first 
by the action of the acid on the milk, must be entirely 
dissolved by continued and careful shaking of the bot- 
tle. Beginners sometimes fail to mix thoroughly the 
milk and the acid in the test bottle. As the acid is 
much heavier than the milk a thin layer of it is apt to 
be left unnoticed at the bottom of the bottle, unless this 
is vigorously shaken toward the end of the operation. 

The mixture becomes hot by the action of the acid on 
the water in the milk and turns dark colored, owing to 
the effect of the strong sulfuric acid on the nitrogenous 
constituents and the sugar in the milk. 

3 



34 Testing Milk and Its Products. 

Colostrum milk or milk from fresh cows will form a 
violet colored mixture with the acid, due to the action 
of the latter on the albumen present in such milk in 
considerable quantities (23). 

When milk samples are preserved by means of potas- 
sium bichromate (190), and so much of this material has 
been added that the milk has a dark yellow or reddish 
color, the mixture of milk and acid will turn greenish 
black, and a complete solution is rendered extremely 
difficult on account of the toughening effect of the bi- 
chromate on the precipitated casein. This difficulty is 
still more pronounced with milk preserved with form- 
aldehyd. 

39. Whirling bottles. After the milk and the acid 
have been thoroughly mixed, the test bottle is at once 
placed in the centrifugal machine or tester and whirled 
for four or five minutes at a speed of 600 to 1200 revo- 
lutions per minute, according to the diameter of the 
tester (66). It is not absolutely necessary to whirl the 
test bottles in the centrifuge as soon as the milk and 
the acid are mixed, although this method of procedure 
is much to be preferred ; they may be left in this condi- 
tion for any reasonable length of time (24 hours, if 
necessary) without the test being spoiled. If left until 
the mixture becomes cold, the bottles should, however, 
be placed in warm water (of about 160° F.) for about 
fifteen minutes before whirling. 

Four minutes at full speed is sufficient for the first 
whirling of the test bottles in the centrifuge; this will 
bring all fat to the surface of the liquid in the bottle. 



*The Babcock Test. 



35 



40. Adding water. Hot water is now added by means 
of a pipette or some special device (10 in fig. 58),^ until 
the bottles are filled to near the scale on the neck (80). 
The bottles are whirled again at full speed for one min- 
ute, and hot water added a second time, until the iower 
part of the column of fat comes within the scale on the 
neck of the test bottle, preferably to the 1 or 2 per 
cent, mark, so as to allow for the sinking of the column 
of fat, due to the gradual cooling of the contents of the 
bottle. By dropping the water directly on the fat in 
the second filling, the column of fat will be washed free 
from light flocculent matter, which might otherwise be 

entangled therein and render the 
reading uncertain or too high. A 
final whirling for one or two min- 
utes completes the separation of 
the fat. 

41. Measuring the fat. The 
amount of fat in the neck of the 
bottle is measured by the scale or 
graduations on the neck. Each 
division of the scale represents 
two-tenths of one per cent, of fat, 
and the space filled by the fat 
shows the per cent, of butter fat 
contained in the sample tested. 

The fat is measured from the 
lower line of separation between 
the fat and the water, to the top of the fat column, at 
the point h, shown in the figure, the reading being thus 
taken from a to b, and not to c or to d. Comparative 




— - (, 



Fig. 10. Moasuring the 
column of fat in a 
Babcock test bottle. 



^ See imder 204. 



36 Testing milk and its Products. 

gravimetric analyses have shown that the readings ob- 
tained in this manner give correct results. While the 
lower line of the fat column is nearly straight, the upper 
one is curved, and errors in the reading are therefore 
easily made, unless the preceding rule is observed. 

Results with 8% bottles (44a) agree well with those 
obtained with the 10% bottles, when care is taken to 
read the fat column to the extreme top of the menis- 
cus. This appears especially thin in the former bottles 
and cannot be seen quite as readily as in the 10% 
bottles. 

The fat obtained should form a clear yellowish liquid 
distinctly separated from the acid solution beneath it. 
There should be no black or white sediment in or below 
the column of fat, and no bubbles or foam on its sur- 
face. The bottles must be kept warm until the read- 
ings are made, so that the column of fat will have a 
sharply defined upper and lower meniscus. When the 
testing is done in a cold room, it is a good plan to place 
the bottles in a pail with water of 140° F. be- 
fore readings are made. The readings should always 
be made when the fat has a temperature of about 140° 
F. ; too low results will be obtained if the fat is allowed 
to cool below 120° F., and too high if readings are 
taken above 150°. The fat separated in the Babcock 
test solidifies at about 100° F. If the fat is partly sol- 
idified, it is impossible to make an accurate reading.^ 

^ The effect of differences in the temperature of the fat on the read- 
ings obtained will be seen from the following: If 110 and 150° F, be 
taken as the extreme temperatures at which readings can be made, 
this difference of 40" F. (22.3° C.) would maKo a difference in the vol- 
ume of the fat column obtained in the case of 10 per cent, milk of 
.00064 x2x22.8=.028544 cc, or .14 per cent., .00064 being the expansion 
coefficient of pure butter fat per degree Centigrade between 50 and 100° 



The Bahcoch Test. 37 

42. Readings of tests of milk made in steam turbine 
testers with tightly closed covers which prevent the free 
escape of exhaust steam (71), will come .2 to .3 per cent, 
too high if the temperature of the fat is allowed to rise 
to that of the exhaust steam during the process of whirl- 
ing. In such cases the test bottles must be allowed to 
cool to about 140°, by placing them in water of this 
temperature for a few minutes, before readings are 
taken.^ 

A pair of dividers will be found convenient for meas- 
uring the fat, and the liability of error in reading is 
decreased by their use. The points of the dividers are 
placed at the upper and lower limits of the fat column 
(from a to & in fig. 10). The dividers are now lowered, 
one point being placed at the zero mark of the scale, 
and the mark at which the other point touches the scale 
will show the per cent, of fat in the sample tested. 
The dividers must be tight in the joint to be of use for 
this purpose. 

B.— Discussion of the Details of the 
Bab COCK Test. 

4^. The main points to be observed as to apparatus 
and testing materials in order to obtain correct and 
satisfactory results by this test will now be considered, 
and such suggestions and help offered as have been 
found needful from past experience with a great variety 
of samples of milk, apparatus, and accessories. 



C. {Zune, Analyse dcs Beurrcs, I, 87), and 2^ the volume of the fat in 
cc. contained in 17.6 cc. of 10 per cent. milk. On 5 per cent., milk this 
extreme difference would therefore be about .07, or nearly .1 of 1%. 
1 See Wis. Expt. Sta. rep., XVII, p. 76. 



38 Testing Milk and Its Products. 

1.— Glassware. 

44. Test bottles. The test bottles should have a ca- 
pacity of about 50 cc, or less than two ounces; they 
should be made of well-annealed glass that will stand 
sudden changes of temperature without breaking, and 
should be sufficiently heavy to withstand the maximum 
centrifugal force to which they are likely to be sub- 
jected in making tests. This force may, on the average, 
be not far from 30.65 lbs. (see 66), which is the pres- 
sure exerted in whirling the bottles filled with milk and 
acid in a centrifugal machine of 18 inches diameter at 
a speed of 800 revolutions per minute. 

"When 17.6 cc, or 18 grams of milk (48), are meas- 
ured into the Babcock test bottle, the scale on the neck 
of the bottles will show directly the per cent, of fat 
found in the milk. The scale is graduated from to 
10 per cent. 10 per cent, of 18 grams is 1.8 grams. As 
the specific gravity of pure butter fat (i. e., its weight 
compared with that of an equal volume of pure water) 
at the temperature at which the readings are made 
(about 140° F.), is 0.9, then 1.8 grams of fat will oc- 
cupy a volume of i^^?^^2 cubic centimeters. The space 
between the and 10 per cent, marlis on the necks of 
the test bottles must therefore hold exactly 2 cubic cen- 
timeters. The scale is divided into 10 equal parts, each 
part representing one per cent., and each of these is 
again sub-divided into five equal parts. Each one of the 
latter divisions therefore represents two-tenths of one per 
cent, of fat when 17.6 cc. of milk is measured out. The 
small divisions are sufficiently far apart in most Bab- 
cock test bottles to make possible the estimation of one- 



The Bahcock Test. 39 

tenth, or even five-liundredtlis, oi one per cent, of fat 
in the samples tested. 

In the best kinds of Babcock bottles the per cent, 
marks are complete circles and the half per cent, 
marks are semi-circles. This greatly aids in making 
correct readings. 

As the necks of Babcock test bottles vary in diame- 
ter, each separate bottle must be calibrated by the manu- 
facturers ; the length of the scale is not, for the reasons 
given, apt to be the same in different bottles.^ 

If the figures and lines of the scale become indistinct 
by use, the black color may be restored by rubbing a 
soft pencil over the scale, or by the use of a piece of 
burnt cork after the scale has been rubbed with a little 
tallow. On wiping the neck with a cloth or a piece of 
paper the black color will show in the etchings of the 
glass, making these plainly visible. 

Special forms of test bottles used in testing cream 
and skim milk are described under the heads of cream 
and skim-milk testing (89, 90, 99). 

44a. Eight-per-cent. bottles. Milk test bottles with 
scale graduated from to 8 per cent, have come into 
general use of late years, having been adopted in 1911 
by the National Dairy Instructors' Association as 
"standard." The specifications for this bottle and 
other Babcock glassware are given in par. 307. 

45. Marking test bottles. Test bottles can now be 
bought with a small band or portion of their neck or 
body ground or ''frosted," for numbering the bottles 
with a lead pencil. Bottles without this ground label 
can be roughened at any convenient spot by using a wet 
fine file to roughen the smooth surface of the glass. 



4U 



Testing Milk and Its Products. 



There is this objection to the latter method that, unless 
carefully done, it is apt to weaken the bottles so that 
they will easily break, and to both methods, that the 
lead pencil marks -made on such ground labels may be 
effaced during the test if the bottles are not carefully 
handled. Small strips of tin or copper with a number 
stamped thereon are sometimes attached as a collar 
around the necks of the bottles. They are, however, 
easily lest, especially when the top of the bottle is 
slightly broken, or at any rate, are soon corroded so 
that the numbers can only be seen with difficulty. 

The best and most permanent label for test bottles is 
made by scratching a number with a marking diamond 
on the glass di- 
rectly above the 
scale on the neck 
of the bottles or 
by grinding a 
number on the 
bottle itself. In 
ordering an out- 
fit, or test bottles 
alone, the oper- 
ator may specify 

that the bottles fig. 12. Waste-acld jar, 

are to be marked 1 to 24, or as many as are bought, 
and the dealer may then put the numbers on with a 
marking diamond. 

A careful record should be kept of the number of the 
bottle into which each particular sample of milk is 
measured. Mistakes often happen when the operator 




The Babcock Test. 



41 



trusts to his memory for locating the different bottles 
in which tests are made at the same time. 

46. Cleaning test bottles. The fat in the neck of 
the test bottles must be liquid when these are cleaned. 




Fig. 13. Apparatus for cleaning test bottles. A, apparatus in posi- 
tion ; the water flows from the reservoir through the iron pipe 6 into 
the inverted test bottle d through the brass tube c, screwed into the 
iron pipe. B shows construction of the rubber support on which the 
test bottles rest ; /, sint:. 

In emptying the acid the bottle should be shaken in 
order to remove the white residue of sulfate of lime, 
etc., from the bottom; if the acid is allowed to drain 
out of the bottle without shaking it, this residue will 



42 



Testing MUk and Its Products. 



be found to stick very tenaciously to the bottom of the 
bottle in the subsequent cleaning with water. 

A convenient method of emptying test bottles is shown 
in the illustration (fig. 12). After reading the fat col- 
umn, the bottles are placed neck down, in the half -inch 
holes of the board cover of a five-gallon stoneware jar. 
An occasional shaking while the liquid is running from 
the bottles will rinse off the preciptate of sulfate of 
lime A thorough rinsing with boiling hot water is 
generally sufficient to remove all grease and dirt, as 
well as acid solution from the inside of the bottles, 
The apparatus shown in fig. 13 will be found convenient 
for this purpose. After the bottles have been rinsed a 
second time, they may be placed in an inverted posi- 
tion to drain, on a galvanized iron rack, as shown in 
fig. 14, where they are kept until needed. The outside 

of the bottles should 
occasionally be wiped 
clean and dry. 
. 47. The amount of 
unseen fat that clings 
to test bottles, used 
for testing milk or 
cream, is generally not sufficient to be noticed in test- 
ing whole milk, but it plays an important part in test- 
ing samples of separator skim milk. It may be readily 
brought to light by making a blank test with clean 
water in bottles used for testing ordinary milk, which 
have been cleaned by simply draining the contents and 
rinsing once or twice with hot water; at the conclusion 
of the test the operator will generally find that a few 




Fig. 14. Draining racls for test bottles. 



The Babcock Test. 



43 



drops of fat will collect in the neck of the bottles, some- 
times enough to condemn a separator. 

Boiling hot water will generally clean the grease from 
glassware for a time, but all test bottles should, in ad- 
dition, be given an occasional bath in some weak alkali 
or other grease-dissolving solution. Persons doing con- 
siderable milk testing will find it of advantage to pro- 
vide themselves with a small copper tank, fig. 15, 
which can be filled with a weak alkali-solution. After 
having been rinsed with hot water, the test bottles are 
placed in the hot solution in the tank, where they may 
be left completely covered with the liquid. If the tank 
is provided with a small faucet at the bottom, the liquid 
can be drawn off when the test bottles are wanted. A 
tablespoonful of 
some cleaning pow- 
der to about two 
gallons of water 
will make a very 
satisfactory solu- 
tion ; sal soda, 
Gold Dust, Lewis' 
lye or Babbitt's 
potash are very 
efficient for this 
purpose. The 
cleansing proper- 
ties of solutions of 
any of these sub- , 
stances are in- 
creased by warm- 
ing the liquid. The fig. 15. Tank for cleaning test bottles. 




44 



Testi7ig Milk and Its Products. 



test bottles must be rinsed twice with hot water aftei 
they are taken from this bath. 

An excellent cleaning solution that can be used for 
a long time, may be made of one-half pound bichromate 
of potash to one gallon of sulfuric acid.^ 

47a. An arrangement for cleaning a number of test 
bottles at the same time is shown in Hq-. 16.^ Ill shows 




I 

Fig. 16. 



.IT M 

A convenient device for cleaning test bottles. 



the frame in which the bottles are placed, one in each 
socket; the metal plate E is put over the necks of tL'^ 
bottles which pass through the holes in it up to the 
shoulder of the bottles. The pins F, F, are then pushed 
through holes in the rods D-D, and the plate and bot- 
tles thus firmly held in the crate. When secured in 
this way, the frame full of bottles may be placed in a 
pail or tank of hot water as in I. They will soon fill 
with water and the time of filling the bottles one at a 
time thus saved. When ready to empty the bottles, the 

^ Michels, Am. Cheesemaker, Jan. 1903. 
* Wisconsin experiment station, bull. 129. 



The Bahcock Test. 



45 



frame is reversed and placed in the position shown in II. 

One or two rinsings in boiling hot water is usually 
sufficient to effectually clean the bottles, but when they 
have been allowed to get greasy they can be dipped into 
a pail of hot dilute lye; this will saponify the grease 
and after one or two rinsings in clean hot water the 
bottles will be bright and clean. 

The black stains that sometimes stick to the inside of 
test bottles after prolonged use, can be removed with a 
little muriatic acid, or by means of a small stiff brush. 

48. Pipette. The difference in the weights of various 
samples of normal milk generally falls within compara- 
tively narrow limits ; if a given volume of water weighs 
one pound, the same volume of the usual grades of nor- 
mal milk will weigh from 1.029 to 1.033 pounds, or on 
the average, 1.03 lbs. 18 grams of water measures 18 
cc.^ ; 18 grams of milk will therefore take up a smaller 
volume than 18 cc, \iz., 18 divided by 1.03, which is 
very nearly 17.5. This is the quantity of milk taken 
in the Babcock test. A certain amount of 
milk will adhere to the walls of the pi- 
pette when it is emptied, and this thin film 
has been found to weigh about one-tenth 
of a gram; consequently 17.6 cc. has been 
adopted as the capacity of the pipette used 
for delivering 18 grams of milk. 

For convenience in measuring the milk, ^ ^ 

*=• Fig. 17. Pipette 

the shape of the pipette is of importance. . points— 

^ ^ ^ ^ A. proper con- 

The mark on the stem should be two inches struction ; b, 

undesirable 

or more from the upper end of the pip- construction. 



* Cubic centimeters (abbreviated: cc.) are the standard used for 
measurinar volume in the metric system, similar to the quart or pint 



46 Testing Milk and Its Products. 

ette. The lower part should be small enough to fit 
loosely into the neck of the test bottle, and not con- 
tracted to a fine hole at the point; the point should be 
large enough to allow a quick emptying of the pipette 
(fig. 17) and not so large that it is difficult to use it. 
An opening of about % i^- diameter will be found 
satisfactory. 

49. Fool pipettes. Soon after the Babcock test began to be 
generally used at creameries as a basis of payment for the milk, 
a creamery supply house put on the market a 20 cc. milk-meas- 
uring pipette, which was claimed to show the exact butter value 
of milk, instead of its content of butter fat, as is the case in 
using the ordinary 17.6 cc. pipette. A 20 cc. pipette will de- 
liver 2.4 cc. more milk than a 17.6 cc. pipette, (or 13.6 per cent, 
more), and the results obtained by using these pipettes will, 
therefore, be about 13.6 per cent, too high. In considering the 
subject of Overrun (214) it is noted that the excess of butter 
yield over the amount of fat contained in a certain quantity of 
milk will range from about 10 to 16 per cent., or on the average, 
about 12 per cent. 20 cc. pipettes may. therefore, give approxi 
mately the yield of butter obtained from a quantity of milk, 
but as will be seen, this yield is variable, according to the skill 
of the butter maker and to conditions beyond his control; it can- 
not therefore be used as a standard in the same manner as the 
fat content of milk. Similar 22 cc. pipettes were also sent out. 
These pipettes created a great deal of confusion during the short 
time they were on the market, and were popularly termed ''fool" 
pipettes. It is not known that such pipettes have been sold of 
late years. 

A Wisconsin law makes it a misdemeanor to use in that state 
other than 17.6 cc. pipettes for measuring milk where this is paid 
for by the Babcock test.^ 



measure in our ordinary system of measures. One quart is equal to a 
little less than 1.000 cubic centimeters (1 liter). In the same way, 
grams represent woight, like pounds and ounces. One cc. of water at 
4° Centigrade weighs 1 gram; 1,000 grams (=1 kilogram) are equal to 
2.2 lbs. Avoirdup. (Soo Appendix for Comparisons o/ metric nnd 
customary weiphts and measures.) 
» Laws of 1908. chapter 4.S. 



The Bahcock Test. 47 

50. Acid measures. A 17.5 cc. glass cylinder (fig. 9) 
for measuring the acid is generally included in the out- 
fit, when a Babcock tester is bought. This cylinder an- 
swers every purpose if only occasional tests are made; 
the acid is poured into the cylinder from the acid bottle 
as needed, or a quantity of acid sufficient for the num- 
ber of test bottles to be whirled at a time, is poured 
into a small glass beaker provided with a lip, or into a 
small porcelain pitcher; these may be more easily 
handled than the heavy acid bottle or jug, and the acid 
measure is then filled from such a vessel. 

Where a considerable number of tests are made regu- 
larly, the acid can be measured into the test bottles 
faster and with less danger of spilling, by using some 
one of the many devices proposed for this purpose. 
There is some objection to nearly all of these appliances, 
automatic pipettes, burettes, etc., although they will 
often give good satisfaction for a time while new. Sul- 
furic acid is very corrosive, and operators, as a rule, 
take but poor care of such apparatus, so that it is a 
very difficult matter to design a form which will re- 
main in good working order for a long time. Auto- 
matic pipettes attached to acid bottles or reservoirs, to 
prove satisfactory, must be made entirely of glass, and 
strong, of simple construction, tightly closed and 
quickly operated. 

51. The Swedish acid bottle^ answers these require- 
ments better than any other device known to the writ- 
ers at the present time. Its use is easily understood 
(see fig. 18) ; it gives good satisfaction if the hole in 
the glass stop-cock through which the acid passes has 

' Now jronorally sold and known as the Com1)ined Acid Bottle. 



48 



Testing Milk and Its Products. 



a diameter of at least one-eighth of an inch, as is gener- 
ally the case. We have used or inspected some half a 
dozen other devices placed on 
the market by various deal- 
ers for delivering the acid, 
but cannot recommend them 
for use in factories or outside 
of chemical laboratories. 

52. Instead of measuring out the 
aeid, Bartlett^ has suggested add- 
ing 20 CO. directly to the milk in 
the test bottles, till the mixture 
rises to a mark on the body of the 
bottle at the point where this "will 
hold 37.5 cc, i. e., the total volume 
of milk and acid (83). This method 
of adding the acid is in the line of 
simplicity, but has not become gen- 
erally adopted. If the method is 
used, the marks should be put on 
by the manufacturers, as the oper- 
ator in attempting to do so will be apt to weaken or break the 
bottles. 

Calibration of Glassware. 

53. Test bottles. The Babcock milk test bottles are 
so constructed that the scale of graduation on the neck 
measures a volume of 2 cubic centimeters, between the 
zero and the 10 per cent, marks (44). The standards 
for test bottles and other Babcock glassware adopted by 
the Association of Official Agricultural Chemists of 
America are given at the close of this book (306). It 
will be seen that the limit of error for test bottles is 
one of the smallest graduations on the scale, or .2 per 




Fig. 18. Swedish acid-bottle ; 
tlie side tube is made to 
hold 17.5 cc. of acid. 



^ Maine experiment station, bull. 31. 



The Bahcoch Test. 49 

cent. The correctness of the graduations may be easily 
ascertained by one of the following methods: 

54. (A.) Calibration with water. This may be done 
by means of a delicate pipette or burette, or by weigh- 
ing the water that the graduated portion of the neck 
will hold. 

a, Measuring the water. Fill the test bottle with 
water to the zero mark on the scale; remove any sur 
plus water and dry the inside of the neck with a piece 
of filter paper or clean blotting paper; then measure 
into the bottle 2 cc. of water from an accurate pipette 
or burette, divided to one-twentieth of a centimeter. If 
the graduation is correct, 2 cc. will fill the neck exactly 
to the 10 per cent, mark of the scale. 

b, Weighing the water. Fill the bottle with water 
to the zero mark of the scale and remove any surplus 
water in the neck, as before. Weigh the bottle with the 
water contained therein. Now fill the neck with water 
to the 10 per cent, mark, and weigh again. The differ 
ence between these weights should be 2 grams. 

In all cases where calibrations are to be made, the 
test bottles, or other glassware to be calibrated, must be 
thoroughly cleaned beforehand with strong sulfuric 
acid or soda lye, and washed repeatedly with pure 
water, and dried. Glassware is not clean unless water 
will run freely over its surface, without leaving any 
adhering drops. 

55. (B). The Trowbridge method of calibration.' 
An extremely simple and accurate method of calibrating 
test bottles has been proposed by Mr. 0. A. Trowbridge 
of Columbus, Wis. The capacity of the graduated por- 

1 Hoard's Dairs'inan, March 8, 1901, by DeWitt Goodrich. 
4 



50 



Testing MUk and Its Products. 



tion of the neck of a milk test bottle is measured with a 
piece of metal which is carefully filed to such a size that 
it will displace exactly two cubic centimeters of water. 
He used a thirty-penny wire nail, cutting off the head 
of the nail and attaching to it a short piece of fine wire. 
Manufacturers have improved on this rather crude de- 
vice and standard measures for calibrating 
test bottles can now be bought of dairy 
supply houses (see fig. 19). 

When a test bottle is to be calibrated 
by this standard measure, it is filled with 
water to the zero mark on the neck of the 
bottle. The water adhering to the neck is 
carefully removed with a strip of blotting 
paper, and the measure is then lowered 
into the test bottle, as shown in the illus- 
tration. If the water rises from to 10 
on the neck when the upper point of the 
measure is submerged in the water, the 
scale is correct. If greater variations than 
.2 per cent, occur, the bottle should be re- 
jected. 

The figure shows one of these calibrators 
made in two sections, so that the accuracy 
of the 5 per cent., as well as the 10 per 
cent, mark on the scale may be ascer- 
tained. 

56. The standard measure. In the place 
of an iron nail, as originally proposed, a 

Fig. 19. The 

piece of metal or glass rod may be advan- Trowbridge cai- 
tageously used as a standard measure. The 
standardization of this measure is most conveniently 




The Bahcock Test. 51 

done by weighing. Since the specific gravities of iron, 
copper, brass, and glass are 7.2, 8,7, 8.5, and about 2.7, 
respectively, pieces of these materials replacing 2 cc. of 
a liquid, will weigh 14., 17.4, 17.0 and 5.4 grams, for 
iron, copper, brass and glass in the order given. 

A measure of the right weight may be suspended by 
a very fine copper or platinum wire (melted into the 
glass rod if this material be chosen), and is used di- 
rectly for calibrating test bottles as described above. 
Before a measure so made is used as a standard, its ac- 
curacy should be determined by weighing the amount 
of water of a temperature of 20° C, which it replaces. 
The specific gravity of glass especially, varies somewhat 
according to its composition, so that a standardization 
of a measure by weight alone cannot be depended upon 
to always give correct results. 

In submerging the measure in the test bottle to be 
calibrated, care must be taken that all air bubbles are 
removed before the position of the meniscus of the 
water is noted; if a metal standard measure is used, it 
must be kept free from rust or tarnish. 

57. (C.) Calibration with mercury. 27.10 grams of 
metallic mercury are weighed into the perfectly clean and dry 
test bottle. Since the specific gravity of mercury is 13.55, 
double this quantity will occupy a volume of exactly 2 cubic 
centimeters (48). The neck of the test bottle is then closed 
with a small, smooth and soft cork, or a wad of absorbent cot- 
ton, cut off square at one end, the stopper being pressed down 
to the first line of the graduation. The bottle is now inverted 
so that the mercury will run into its neck. If the total space 
included between the and 10 marks is just filled by the two 
cubic centimeters of mercury, the graduation is correct. 

The mercury may be conveniently transferred from one test 
bottle to another, by means of a thin rubber tube which is 
slipped over the end of the necks of both bottles, and one weigh- 



52 Testing Milk and Its Products. 

ing of mercury will thus suflSce for a number of calibrations. 
In transferring the mercury, care must be taken that none of it 
is lost, and that small drops of mercury are not left sticking to 
the walls of the bottle emptied. A sharp tap on the bottle 
with a lead pencil will help to remove minute drops of mercury 
from the inside. Unless the bottles to be calibrated are per- 
fectly clean and dry, it is impossible to transfer all the mer- 
cury from one bottle to another. 

After several calibrations have been made, the mercury should 
be weighed again in order to make certain that none has been 
lost by the various manipulations. Scales similar to those shown 
under (91) are sufSciently delicate for making these weighings. 

58. Test bottles may also be calibrated with mercury by weigh- 
ing the bottles filled with mercury to the zero mark, and again 
when filled to the 10 mark. This is the official method for test- 
ing bottles adopted by the Association of Official Agricultural 
Chemists (see 306). 

59. Cleaning mercury. Even with the best of care, mercury 
used for calibration of glassware will gradually become dirty, 
so that it will not flow freely over a clean surface of glass. It 
may be cleaned from mechanical impurities, dust, grease, water, 
etc., by filtration through heavy filter paper. This is folded in 
the usual way, placed in an ordinary glass funnel and its point 
perforated with a couple of pin holes. The mercury will pass 
through in fine streams, leaving the impurities on the filter 
paper. Mercury may be freed from foreign metals, zinc, lead, 
etc., sometimes noticed as a grayish, thin film on its surface, 
by leaving it in contact with common nitric acid for a number 
of hours; the mercury is best placed in a shallow porcelain or 
graniteware dish and the nitric acid poured over it, the dish 
being covered to keep out dust. The acid solution is then care- 
fully poured off and the mercury washed with water; the latter 
is in turn poured off, and the last traces of water absorbed by 
means of clean, heavy filter paper. 

The mercury to be used for calibration of glassware should 
be kept in a strong bottle, closed by an ordinary stopper. In 
handling mercury, care must be taken not to spill any portion 
of it; finger-rings should be removed when calibrations with mer- 
cury are to be made. 

Mercury forms the .most satisfactory and accurate material 
for calibration of test bottles, on account of its heavy weight 



The Babcock Test. ^ 53 

and the ease with which it may be manipulated. Equally correct 
results may, however, with proper care be obtained by using 
water for the calibration. 

60. Intermediate divisions. The space between 
and 10 on the scale of the Babcock test bottle is divided 
into 50 divisions, each five of which, as previously- 
shown, represent 1 per cent. (44). Since these in- 
termediate divisions are generally made with a dividing 
machine, they are as a rule correct, but it may happen 
that they have been inaccurately placed, although the 
space between and 10 is correct. The accuracy of the 
intermediate divisions can be ascertained by sliding 
along the scale a strip of paper upon which has been 
marked the space occupied by one per cent., and com- 
paring this space with those of each per cent, on the 
scale. 

61. Calibration of skim milk test bottles. The 
value of each division on the common double-necked 
skim milk bottles (99) is one-twentieth, or .05 of one 
per cent. ; there are ten of these divisions in the whole 
scale which, therefore, measures .5 per cent, of fat. It 
requires very careful work to calibrate this scale and it 
is best done by weighing the amount of mercury which 
will just fill the space of ,1 cc. between the first and the 
last divisions (53) ; the correct weight of this mercury 
is 1.355 grams. 

62. Calibration of cream test bottles. The cream bot- 
tles may be calibrated by any of the methods given for 
milk bottles. The neck of a creani test bottle that meas- 
ures thirty per cent, fat will hold 6 cc, and 6 grams of 
water or 81.30 grams of mercury. 

The Trowbridge method of calibrating milk test bot- 



54 Testing Milk and Us Products. 

ties will also be found convenient for cream bottles and. 

the same standard measure us.ed, the part of the scale 

from to 10 being calibrated first, then that from 10 to 

. 20, 20 to 30, 30 to 40 per cent., etc., in the same way. 

63. Pipette and acid cylinder. The pipette and the 
acid cylinder used in the Babcock test may be calibrated 
by any of the methods already given. Sufficiently ac- 
curate results are obtained by weighing the quantity of 
water which each of these pieces of apparatus will de- 
liver, viz., 17.5 grams. The necessity of previous thor- 
ough cleaning of the glassware is evident from what has 
been said in the preceding. The pipette and the acid 
measure may be weighed empty and then again when 
filled to the mark with pure water, or the measureful of 
water may be emptied into a small weighed vessel, and 
this weighed a second time. In either case the weight 
of the water contained in the pipette or acid measure is 
obtained by dilt'erence.^ 

Calibrations of the acid cylinder are generally not 
called for, except as a laboratory exercise, since small 
variations in the amount of acid measured out do not 
affect the accuracy of the test. 

2.— Centrifugal Machines. 

64. The capacity of the testing machine to be selected 
should be governed by the number of tests which are 
likely to be made at one time. For factory purposes a 

1 One cubic centimeter of distilled water weighs 1 gram, when 
weighed in a vacuum at the temperature of the maximum density of 
water (4° C.) ; for the purpose of calibration of glassware used in the 
Babcock test, sufficiently accurate results are, however, obtained by 
weighing the water in the air and at a low room temperature (60° F.) 



The Bahcock Test. 55 

twenty-four or a thirty-two bottle tester is large enough, 
and to be preferred to a larger tester, even if a large 
number of samples are to be tested at a time. The 
operator can use his time more economically in running 
a machine of this size than one holding fifty or sixty 
bottles; the work of filling or cleaning the bottles and 
measuring the fat can be done while the tester is run- 
ning if a double supply of bottles is at hand. Large 
testers require more power than smaller ones, and when 
sixty tests are made at a time, the fat column in many 
bottles will get cold, before the operator has time to 
read them, unless special precautions are taken for 
keeping the bottles warm. 

65. The tester should be securely fastened to a solid 
foundation and set so that the revolving wheel is level. 
The latter must be carefully balanced in order that the 
tester may be run smoothly at full speed. A machine 
that trembles when in motion is neither satisfactory nor 
safe, and the results obtained are apt to be too low. 
High-standing machines are more likely to cause trouble 
in this respect than low machines, and should there- 
fore be subjected to a severe test before they are ac- 
cepted. 

If all sockets are not filled with bottles when a test 
is to be made, the bottles must be placed diametrically 
opposite one another so that the machine will be bal- 
anced when run. The bearings 'should be kept clean and 
be oiled with as much care as the bearings of a cream 
separator. 

The cover of the machine should always be kept 
closed while the bottles are whirled, and should not be 



56 Testing MUk and Its Products. 

removed until the macliine stops; it should be tight 
fitting, since test bottles sometimes break while the ma- 
chine is running at full speed, and every possible pre- 
caution should be taken to protect the operator from 
any danger from spilled acid or broken glass. 

66. Speed required for the complete separation of 
the fat. There is a definite relation between the diame- 
ter of the Babcock testers and the speed required for a 
perfect separation of the fat. In the preliminary work 
with the Babcock test the inventor found that with the 
machine used, the wheel of which had a diameter of 
eighteen inches, it was necessary to turn the crank so 
as to give the test bottles seven or eight hundred revo- 
lutions per minute, in order to obtain a maximum sepa- 
ration of fat; later work has shown that this speed is 
ample. Taking the higher figure as a standard, the cen- 
trifugal force to which the contents of the test bottles 
are subjected when supported on an eighteen-inch wheel 
and turned 800 revolutions per minute, can be calcu- 
lated as follows: 

The centrifugal force, F, acting on the bottles is expressed by 
the formula 

^ = S- •••(!) 

in which w = the weight of the bottle with contents, in pounds j 
v = the velocity, in feet per second, and r = the radius of the 
wheel in feet. 

"When the wheel is turned 800 times a minute, a bottle sup- 
ported on its rim will travel 27rrX 8(Po'' = 2 X3.1415X/2X 1^8 = 62.83 
feet per second. The weight of a bottle, with milk and acid, is 
about 3 ounces, or ,3^ of a pound. Substituting these values 
for V and w, gives 



The Babcock Test. 57 

F= ^^,^^-^5 — 30.65 lbs. 
32.2 Xi«2 

The bottles are, therefore, under the conditions given, sub- 
jected to a pressure of about 30.65 pounds. In order to calcu- 
late the speed required for obtaining this force in case of ma- 
chines of other diameters, the value of v in formula (I) is 
found from 



^^ / 32.2FXr _ _ („) 

1/ w 

Substituting the values for F and w, we have 

^ _ / 32.2 X 30.1)5"r _ 

1/ A 1/5264 r 

In this equation the values r=:5, 6, 7, 8, 9, 10, 11, 12 inches 
are substituted in each case (/g, 1%-, /gj • • 12); and the 
velocity in feet per second then found at which the bottles are 
whirled when placed in wheels of diameters 10 to 24 inches, and 
subjected in each case to a centrifugal force of 30.65 lbs. As 

the number of revolutions per minute ::=„ - , v being as before 

^ 2 Trr' ** 

the velocity in feet per second, and r the radius of the wheel, 
the speed at which the wheel must be turned is found by sub- 
stituting for V the values obtained in the preceding calculations 
in case of wheels of different diameters. The results of these 
calculations are given in the following table: 

Diameter 
of wheel, D. 

10 
12 
14 
16 
18 
20 
22 
24 

These figures show that a tester, e. g., 24 inches in diameter, 
will require less than 700 revolutions per minuate for a perfect 
separation of the fat in Babcock bottles, while a ten-inch tester 
must have a speed of nearly 1100 revolutions in order to obtain 
the same result. 



Velocity in feet 


Number of revolutions 


per second, v. 


of wheel per minute. 


46.84 


1074 


51.31 


980 


55.43 


909 


59.26 


848 


62.84 


800 


66.24 


759 


69.47 


724 


72.56 • 


693 



58 Testing Milk and Its Products. 

The speed at which testers of different diameters should be 
run to effect a complete separation has been calculated by Prof. 
C. L. Beach in the following manner.^ The same standard as 
before is taken, viz., 800 revolutions for an 18-inch tester (radius 
9 inches) ; then if x designate the radius of the tester and y the 
speed required, we have 

xy2=r9X800=', or 



/ 9X800'^ 
1/ ~~^~ 

The figures obtained by the use of this formula are similar 
to those given in the preceding table. 

67. To find the number of turns of the handle corre- 
sponding to the number of revolutions made by the 
wheel, the handle is given one full turn, and the number 
of times the wheel revolves, is noted. If the wheel has 
a diameter of 20 inches and revolves 12 times for one 
turn of the handle, the latter should be turned W^^GS 
times a minute (see table), or about once every second, 
in order to effect a maximum separation of fat. By 
counting the number of revolutions, watch in hand, 
and consulting the preceding table, the operator will 
soon know the speed which must be maintained in case 
of his particular machine. It is vitally important that 
the required speed be always kept up ; if through care- 
lessness, worn-out or dry bearings, low steam pressure, 
etc., the speed is slackened, the results obtained will be 
too low ; it may be a few tenths, or even more than one 
per cent. Care as to this point is so much the more 
essential, as the results obtained by too slow whirling 
may seem to be all right, a clear separation of fat and 

* Private communication. 



The Babcock Test. 59 

good duplicates being often obtained, even when the 
fat is not completely separated. 

68. Ascertaining the necessary speed of testers. In 
buying a tester the operator should first of all satisfy 
himself at what speed the machine must be run to give 
correct results ; the preceding table will serve as a guide 
on this point. He should measure out a dozen tests of 
the same sample of milk, and whirl half the number at 
the speed required for machines of the diameter of his 
tester. Whirl the other half at a somewhat higher 
speed. If the averages of the two sets of determinations 
are the same, within the probable error of the test (say, 
less than one-tenth of one per cent.), the first whirling 
was sufficient, as it is believed will generally be the case. 
If the second set of determinations come higher than the 
first set, the first whirling was too slow, and a new series 
of tests of the same sample of milk should be made to 
ascertain that the speed in the second set" of determina- 
tions was sufficient. 

This method will test not only the speed required 
with the particular machine at hand, but will also serve 
to indicate the correctness of the calibration of the bot- 
tles. A large number of tests of the same sample of 
milk made as directed (pouring the milk once or twice 
previously to taking out a pipetteful for each test) 
should not vary more than two-tenths of one per cent, 
at the outside, and in the hands of a skilled operator 
will generally come within one-tenth of one per cent. 
If greater discrepancies occur, the test bottles giving 
too high or too low results should be further examined, 
and calibrated according to the directions already given 
r53 et seq.). 



60 



Testing Milk and Its Products. 




69. Hand testers. When only a few tests are made 
at a time, and at irregular intervals, as in case of dairy- 
men who test single cows in their 
herds, a small hand tester answers 
every purpose. These may be had in 
sizes from two to twelve bottles. In 
selecting a particular make of tester 
.. n. . the dairyman has the choice of a large 

r'lii. 20. Type of "^ * 

Babcock hand testers, number of different machines. Most of 
the first machines placed on the market for this purpose 
were so cheaply and 
poorly constructed as 
to prove very unsat- 
isfactory after hav- 
ing been in use for a 
time. The competi- 
tion between manu- 
facturers of dairy 
supplies and the 
clamor of dairymen 

for something cheap, ^^^- ^l- Type of Babcock hand testers. 

fully account for this condition of affairs. This ap- 
plies especially to the early machines made with belts 
or friction application of power. Hand testers made 
with, cog-geared wheels can be depended on to give the 
necessary speed when run according to the manufactur- 
ers* directions; the earlier machines of this kind were 
very noisy, but at the present time the best machines 
on the market are of this type. These are provided 
with spiral cog-gearing and ball bearings, are strongly 
made and will run smoothly and with little noise (figs 




The Bahcock Test. 



61 



20 and 21) ; in cog-geared machines the bottles are al- 
ways whirled at the speed "which the number of turns 
made by the crank would indicate. 

70. Power testers. For factory purposes, steam tur- 
bine machines (figs. 22-24) are most satisfactory when 
well made and well cared for. They should be pro- 
vided with a speed indi- 
cator and steam gauge, both 
for the purpose of knowdng 
that sufficient speed is at- 
tained, and to prevent what 
may be serious accidents 
from a general smash-up, if 
the turbine ''runs wild" by 
turning on too much steam. 
The revolving wheel of the 
tester should be made of 
wrought or malleable iron, or 
of wire, so that it will not be broken by the centrifugal 
force and cause accidents. The swinging pockets 
which hold the test bottles in most machines should 
be so made that the bottles will not strike . the 
center of the revolving frame w^hen in a horizontal posi- 
tion. Tests have often been lost by the end of the neck 
catching at the center, the bottles thus failing to take 
an upright position when the whirling stops. 

71. The exhaust steam pipe of turbine testers should 
not have too many turns or be much reduced in size 
from that of the opening in the tester. A free escape 
of the exhaust steam is necessary to prevent the steam 
from collecting in the test bottle chamber and overheat- 
ing the test bottles when whirled (41). 




Fig. 22. Type of Babcock steam 
turbine testers. 



62 



Testing Milk and Its Products. 



The cover of the tester should have an opening pro- 
vided with a sliding damper or some arrangement by 
which it can be closed when desired. If whole milk or 
cream is being tested, this hole should be open so that a 
draft of air may enter the chamber dur- 
ing the whirling, and force the steam 
into the exhaust pipe. If skim milk is 
being tested, the opening in the cover 
should be closed. This 
shuts off the draft of 
air, and the exhaust 
steam heats the test 
bottles during whirl- 
ing to 200° F. in some 
cases. This high tem- 
perature aids in sepa- 
rating the fat in skim 

milk and gives fairly Fig. 23. Typu ol i^uucock steam turbine 

testers. 



correct tests of 
samples containing 
less than one-tentli 
per cent, fat (98). 
Some turbine test- 
ers are provided 
with holes in the 
'Overs and damp- 
'^ ers and a thermo- 
meter is placed in 
the cover. 





24. Type ui liabcock turbine testers 
(for testing trenm in JJ-in. cream bottles). 



The Bahcock Test. 



63 



Babcock testers run by electricity have lately been 
put on the market by a couple of manufacturers (fig. 
25). Where no 
steam, but elec- 
trical current is 
available, these 
machines may 
be installed to 
great advantage, 
as they are con- 
venient to use 
and may be de- 
pended on to 
run at the re- 
quired speed. 
S'Ome provision 
for getting hot 
water must be at hand in using electrical Babcock testers/' 

3.— Sulfuric Acid. 
72. The sulfuric acid to be used in the Babcock test 
should have a specific gravity of 1.82-1.83.- Commer- 
cial sulfuric acid (sometimes called oil of vitriol) is 
always used; it can be bought for about 2 cents a 
pound in carboy lots and 25 cents or less a quart at re- 
tail. One quart of acid is sufficient for fifty tests. The 
acid should be kept in glass bottles or jugs, prefer- 
ably glass or rubber stoppered ones, since a cork stop 




Fig. 25. Type of Babcock electrical testers. 



1 The method of installation of a 40-bottle electrical Babcock tester is 
described in detail in Rept. Dept. of Health, City of Chicago, 1906, p. 18. 

' A specific gravity of 1.82 means that a given volume of the acid 
weighs 1.82 times as much as the same volume of water at the same 
temperature (see also under Lactometer, 109). 



64 Testing Milk and Its Products. 

per is soon dissolved by the acid and rendered useless. 
If the bottle is left uncorked, the acid will absorb 
moisture from the air and after a time will become too 
weak for use in this test. 

Lead is the only common metal which is not dissolved 
by strong sulfuric acid ; where considerable milk testing 
is done, it is therefore desirable to provide a table cov- 
ered with sheet lead on which the acid may be handled. 
The acid dissolves iron, tin, wood and cloth, and 
burns the skin. If acid is accidently spilled, plenty of 
water should be used at once to wash it off. Ashes, 
potash, soda, and ammonia neutralize the action of the 
acid, and a weak solution of any one of these alkalies 
should be used after the acid has been washed off with 
water. The red color caused by the action of the acid 
on clothing can be removed by wetting the spot with 
weak ammonia water; the ammonia must, however, be 
applied while the stain is fresh, and is in its turn 
washed off with water. 

73. Testing the strength of acid. The strength of 
the acid can be easily tested by the use of a balance like 
that shown in fig. 34 (91). A dry test bottle is weighed, 
and then filled with acid exactly to the zero mark, or 
to any other particular line of the scale. It is then 
again weighed accurately; the difference between the 
two weights will give the weight of the acid in the bot- 
tle. The bottle is then emptied and thoroughly rinsed 
with water (until the water has no longer an acid 
taste) ; it is then filled with water to the same line as 
before and weighed; the difference between this weight 
and that of the empty bottle gives the weight of the 



The Bahcock Test. 65 

same volume of water as that of the acid weighed. The 
specific gravity of the acid is obtained by dividing the 
weight of the acid by the weight of the water. If the 
quotient comes between 1.82 and 1.83 the acid is of 
correct strength. The outside of the test bottle should 
always be wiped dry before the liquids are weighed. 
Unless great care is taken in measuring the acid and the 
water, and in weighing both these and the test bottle, 
the results obtained will not be trustworthy. 

74. Acid that is a little too strong can be used by 
taking less than the required amount for each test, e. g., 
about 15 cc. Operators are warned against reducing 
the strength of the acid by adding water to it, as acci- 
dents may easily occur when this is done. A too strong 
acid can, if desired, be weakened by simply leaving the 
bottle uncorked for a time, or by pouring the acid into 
a bottle containing a small quantity of water. In the 
'atter case the first portions of acid should be added 
carefully, a little at a time, shaking the bottle after 
each addition, so as not to cause it to break on account 
of the heat evolved in mixing the acid and the water. 
Never dilute sulfuric acid hy pouring water into it. 

A helpful suggestion for using acid that is too strong 
or would give a charred fat oh account of high tem- 
perature of acid or milk, or both, has been made by M. 
L. Holm, Assistant Chemist Chicago Dept. of Health, 
viz., to add 2 cc. of 80 per cent, glycerin (80 parts of 
commercial glycerin and 20 parts of water, by volume) 
to the milk sample, prior to adding the acid.^ The gly- 



1 American Food Journal, 1907, No. 7, p. 28 ; Hoard's Dairyman, Nov. 
8, 1907. 



66 Testing Milk and Its Products. 

ceriu protects the milk to some extent from the acid be- 
fore the two are mixed, and a clear fat may thus often 
be secured under otherwise unfavorable conditions. The 
results appear not to be influenced by the addition of 
the glycerin. 

75. If the acid is a little too weak, correct results 
may be obtained by using more than the specified quan- 
tity, say 20 cc. If a good test is not obtained with this 
quantity of acid, a new lot must be secured, as its spe- 
cific gravity in such a case is below 1.82. The observing 
operator will soon be able to judge of the strength of 
the acid by its action on milk in mixing the two liquids 
in the Babcock test bottles; it is indeed remarkable 
what slight diil:*erences in the specific gravity of the 
acid will make themselves apparent in working the test, 
as regards the rapidity with which both the curdled 
milk is dissolved and the mixture of acid and milk turns 
black. 

76. Strength of sulfuric acid. The relation between 
the strength of sulfuric acid and its specific gravity 
will be seen from the following table: 

Specific Gravity of Sulfuric Acid of Different Strength. 

Specific Oravitv Bui f uric Acid 

flS'C, xcater i'C). (H.,SO^) 

1.841 97 per cent. 

-1.840 96 

1.839 95 

1.837 94 

1.834 93 

1,830 92 

1.825 91 

1.820 90 

1.815 - 89 

1.808 88 



The Babcock Test. 67 

It will be noticed that the sulfuric acid to be used in 

the Babcock test should contain 90 to 92 per cent, of 

acid (H2SO4) ; slightly weaker or stronger acid than 

this may, as previously stated, be used by varying the 

quantity of acid taken for each test according to the 

strength of the acid, but successful tests cannot, as a 

rule, be made with acid weaker than 89 per cent, or 

stronger than 95 per cent. 

77. The Swedish acid tester is a small hydrometer, intended 
to show whether the acid used in the Babcock test is of the cor- 
rect strength. An examination of these testers will show that 
they are practically useless for the purj)0se intended, from the 
fact that they are not sufficiently sensitive; while the testers 
examined were found to sink to the line marked Correct on the 
scale, when lowered into sulfuric acid of a specific gravity of 
1.83, they would sink to a point duch nearer the same mark, 
than to the lines marked Too strong or Too weak, respectively, 
when lowered into either too strong or too weak acid. 

78. The color of the fat column an index to the 
strength of the acid used. The strength of the acid 
is indicated to a certain extent hy the color of the fat 
which separates in the neck of the test bottle when milk 
is tested. If the directions given for making the tests 
are carefully followed, the fat separated out will be of 
a golden yellow color. If the fat is light colored or 
whitish, it generally indicates that the acid is too weak, 
and a dark colored fat, with a layer of black material 
beneath it, shows that the acid is too strong, provided 
the temperature of both milk and acid is about 70°. 
[For influence of temperature, see next paragraph.] 
The acid used in the test is not of sufficient strength 
to appreciably attack the fat at ordinary temperatures 
of testing, but a variation in the strength of the acid 



68 Testing Milk and Its Products. 

or in the temperature of the milk influences the in- 
tensity of the acticn of the acid on the fat, as shown in 
the color of the fat obtained. - 

The following experiment shows the relation between 
the strength of the acid, the temperature of the milk, 
and the color of the fat: 

First: — From a sample of milk measure the usual quantity 
for testing into each of three bottles, A, B and C. Place A in 
iced water, and C in warm water, leaving bottle B at ordi- 
nary temperature. After the bottles havb been left for ten min- 
utes under these conditions, add the normal quantity of acid 
to each and proceed with the test in the ordinary manner. 

Second: — Measure some of the same milk into three other 
bottles, D, E and F. Into test bottle D pour the usual amount 
of rather weak acid; add the same amount of acid of norma] 
strength (1.82-1.83) to bottle E, and add 17.5 cc. of a still 
stronger acid (concentrated sulfuric acid, sp. gr. 1.84), in test 
bottle F; complete the tests in the usual way. 

On the completion of the preceding six tests the operator will 
notice that the fat in the necks of test bottles A (cold millc) 
and D {weak acid) is much lighter colored than that in C {warm 
milk) and F {strong acid), and that the color of the fat in B 
{normal temperature) and E {normal acid) is somewhere be- 
tween that of these two series. 

79. Influence of temperature on the separation of 

fat. The intensity of the action of the sulfuric acid 
on the milk is influenced by the temperature of either 
liquid; the higher the temperature, the more intense 
will be the action of the acid on the solids of the milk. 
It may be noticed that acid from the same carboy will 
act differently on milk in summer than in winter time, 
if the acid and the milk are not brought to a tempera- 
ture of about 70° before testing during both seasons. 
The temperature of the liquids may be as low as 40° P. 
in winter and as high as 80° F. in summer. This dif- 



The Babcock Test. 69 

ference of forty degrees will often have considerable 
influence on the clearness of the fat separated, show- 
ing white curdy substances and a light colored fat in 
winter, or black flocculent specks, with a dark colored 
column of fat in summer. Both these defects can be 
avoided, when the acid is of the proper strength, by 
bringing the temperature of the milk and the acid to 
about 70° F. before the milk is tested. 

The operator should be particularly cautious against 
over-heating either milk or acid, since the heat intensi- 
fies the action of the acid and this may become so vio- 
lent as to force the hot liquid out of the neck of the 
test bottle when the acid is added to the milk, thus 
spoiling the test and possibly causing an accident. 

4.— Water to be used in the Babcock Test. 

8o. Rain water, condensed steam, or soft water should 
be used for the purpose of bringing the fat into the 
neck of the test bottles. The surface of the fat column 
will then usually be clear and distinct. The foam or 
bubbles that sometimes obscure the upper line (menis- 
cus) of the fat, making indistinct the point from which 
to measure it, is generally caused by the action of the 
acid on the carbonates in hard water. The carbonic 
acid gas liberated from such water by the sulfuric acid 
is held more or less by the viscid fat and produces a 
layer of foam on its surface. If clean soft water cannot 
be obtained for this purpose, hard water may be used, by 
adding a few drops of sulfuric acid to the water before 
it is heated, thus causing the carbonic acid to be ex- 



70 Testing Milk and Its Products. 

pelled. By simply boiling, many hard waters will be 
rendered soft and adapted to use in the Babcock test, 
as most of the carbonates which cause this foaming are 
thereby precipitated. 

If the test has been completed, and a layer of foam 
appears over the fat, it may be destroyed by adding a 
drop or two of alcohol. If this is done, the fat column 
should be read at once after the alcohol is added, as 
the latter will soon unite with the fat and increase 
its volume. (See also 96 on the use of glymol in cream 
testing.) 

8i. Reservoir for water. When only a few tests are 
made at one time, hot water can be added with the 17.6 
cc. pipette. If many tests are made, the water may be 
conveniently and quickly filled into the test bottles by 
drawing it from a small copper reservoir or tin pail 
suspended over the testing machine.^ The flow of water 
through a rubber tube connected with the reservoir, is 
regulated bj*" means of a pinch cock. The water must 
be hot when added to the test bottles so as to keep the 
fat in a melted condition until the readings are taken. 
Most turbine testers are now made with a very conven- 
ient water reservoir attached to the tester (figs. 22-24). 

The use of zinc or steel oilers, or perfection oil cans 
has been suggested as a convenient method of adding 
hot water to the test bottles, but most operators prefer 
to add water to the bottles by means of a piece of rub- 
ber tubing connected Avith a reservoir, as shown in the 
illustrations just referred to. 

^ Ordinary tinware will soon rust with water standing in it, and cop- 
per reservoirs are therefore more economical. 



The Babcock Test. 



71 



5.— Modifications op the Babcock Test. 

82. The Russian milk test. . The same chemical and me- 
chanical principles applied in the regular Babcock test, are used 
in the Russian milk test, except that in this ease the machine in 
which the bottles are whirled, and the bottles themselves, are so 
constructed that the latter can be filled with hot water while 
the machine is running^, thus saving time and the trouble inci- 
dent to the stopping of the tester and filling the bottles by 
means of a pipette. The milk-measuring pipette (fig. 28) and 




Fig. 26. The Russian test. 



the acid measure used in the Kussian test are one-half of the 
ordinary size, and the test bottles are made in two pieces with 
a detachable narrow graduated stem (see fig. 27). The machine 
is substantially made of cast iron; it is provided with a speed 
indicator which shows at any time the number of revolutions at 
which the bottles are being turned. The accompanying illustra- 
tions show the apparatus used in this test. When the directions 
for operating the test are followed closely, the results obtained 
are accurate and very satisfactory. 



* A similar arrangement for the regular Babcock test has been 
suggested by Mitchell and Walker of Kingston (Ont.) Dairy School 
(see Ont. Dept. of Agriculture, bull. 170). 



72 



Testing Milk and Its Products. 



83. Bartlett's modification. Bartlett^ proposed a modifi- 
cation of the method of procedure in the Babcock test, which 
aims to simplify the manipulations. 20 cc. of acid are added, 
instead of 17.5 cc, and the bottles filled with the milk-acid 
mixture are left standing for not less than five minutes and then 
filled with hot water to within the scale; the bottles are then 
whirled for five minutes at the regular rate (52). 

83a. Siegfeld's modification. The 
German dairy chemist Siegfeld in 
1899 proposed a modification of the 
Babcock test,^ using 2 cc. of amy! alco- 
hol with the sulfuric acid, and filling 
up with dilute sulfuric acid (1:1, sp. 
gr., 1.5) in one filling, in place of 
water after the whirling. A clear 
separation of the fat is facilitated by 
both these changes, but when properly 
conducted there is no difSculty what- 
ever in obtaining a clear fat column 
in the BabcocK test as described in 
this book, and the modification has not 
therefore been generally introduced in 
American factories. It has, however, 
been adopted in many German creamer- 
ies where the Babcock test is used. 

84. Bausch and Lomb centrifuge. 
Fig. 29 shows a form of hand centri- 
fuge which may be used to advantage 
by physicians or in pathological labora- 
tories for the determination of fat in 
milk. The centrifuge is especially designed for ex- 
amination of urine, sputum, blood, etc., but has 
been adapted to milk analysis by the Leffmann & 
Beam test, a special form of bottle (fig. 30) having been con- 
structed for this purpose. The machine gives satisfactory re- 
sults by the Babcock test as well, provided the acid used is 
1.83-1.84, or if the bottles containing the acid-milk mixture be 
placed in hot water for five or ten minutes prior to the whirling. 

1 Maine experiment station, bull. 31 (s. s.) 
^ Molkerei Ztg., 1899, p. 51. 




Fig. 28. 
TMpette used 
in the Rus- 
sian test. 



Fig. 27 

Test bottle 
used in ilu' 
Russian test. 



The Bahcock Test. 



73 



As the bottles are calibrated for only 5 cc. of milk and the neck 
of the bottles, with scale, is correspondingly fine, testing milk 
with this machine requires some nicety of manipulation not called 
for in case of regular Babcock testers constructed for the use 
of factory operators and dairymen. 




Fig. 30. 

Test bottle and 
pipette for phy 
sician's centri 
fuge. 



Fig. 29. Physician's centri- 
fuge that may be used for milk 
testing. 



840. Whitman milk bottle. Dr. Ross C. Whitman has de 
vised a milk testing bottle for the special use of physicians in 
testing human milk and small amounts of cow's milk by the Bab- 
cock test.^ The bottle, which can be placed in an ordinary urine 
centrifuge, consists of two parts, a small tube for holdiug the 
milk, acid and water, and a detachable graduated fine tube, into 
which the fat column is brought after the final filling and whirl 
ing. 5cc. of milk are used in this test. 



iJour. Amer. Med. Asso., 47 (1906), p. 204. 
Ind. and Eng. Chemistry, 1912, p. 841. 



See also Doran, Jr. 



74 Testing Milk aTid Its Products. 

Questions. 

1. Give a brief description of the Babeock test. 

2. State precautions to be observed in each of the following 
operations: (a) Measuring the milk, (b) adding the acid, (c) 
whirling the bottles, (d) adding the water, (e) measuring the fat. 
If the fat separates clear, but the results are evidently too low, 
what is the probable cause, and how can the correct test be estab- 
lished ? 

3. To what extent does the temperature of the fat, when 
read, influence the result? 

4. Explain the graduations of the milk test bottle. 

5. What is the capacity of the neck of a milk test bottle be 
tween the and 10 marks, expressed in cc, and in grams? 

6. If the graduations of a test bottle measure 2.3 cc. from 
to 10%, what would be the correct test of a sample which reads 
3.4% fat in this bottle? 

7. Describe three different methods of calibrating milk test 
bottles. 

8. Describe the proper construction of the milk-measuring 
pipette; what weight of milk does it deliver? 

9. What is a Swedish acid bottle? 

10. What speed is required for testers having a diameter -^f 
8, 15, and 20 inches? 

11. Write an order for one gallon of sulfuric acid to be used 
in testing. 

12. How can the strength of the acid be tested at the farm or 
in a factory? 

13. State precautions to be taken in using an acid that is 
(a) too strong, (b) too weak. 

14. What does the color of the fat indicate in regard to the 
strength of the acid or the temperature of either acid or milk? 

15. What is the cause of foam above the fat column, and how 
may it be prevented? 

16. What causes white curd or black specks in the fat? 

17. Describe a few modifications of the Babeock test. 

18. In which two points does the Russian miik test mainij' 
differ from the Babeock testt 



CHAPTER IV. 

CREAM TESTING. 

85. Cream may be tested by the Babcock test in the 
same manner as milk, and the results obtained are ac- 
curate when the necessary care has been taken in sam- 
pling the cream and measuring the fat. The composi- 
tion of cream varies greatly according to the process of 
creaming, the temperature of the milk during the cream- 
ing, the quality and the composition of the milk, etc. 
The cream met with in separator creameries will con- 
tain from 25 to 40 per cent, of fat, or on the average 
about 35 per cent. Cream from hand separators may 
be as rich as this, but it often contains only 20 per cent. 




students testing dairy products. 



^5^^- 



76 Testing Milk and Its Products. 

of fat as delivered to creameries. An average grade of 
market cream as retailed contains about 25 per cent, of 
fat. If 18 g-rams of 25 per cent, cream are measured 
into an ordinary Babcock test bottle, there will be 
18X. 25=4.5 grams of pure butter fat in the bottle, 
or, (since the specific gravity of butter fat is about .9) 
^=5 cc. It is shown that the space from to 10 
in the neck of these bottles holds exactly 2 cc. (44). 
The neck of the milk test bottle is not large enough to 
show the per cent, of fat in a sample of cream if 18 
grams are taken for testing, and it is therefore neces- 
sary to adopt special measures when cream is to be 
tested. 

86. Errors of measuring cream. Several factors 
tend to render inaccurate the measuring of cream for 
the Babcock test, and correct results can therefore only 
be obtained by weighing the cream. If a 17.6 cc. pi- 
pette is used in testing the cream, it will not deliver 
18 grams of cream, as it will of milk, for the following 
reasons : 

1. The specific gravity of cream is lower than that of 
milk; if a certain quantity of milk weighs 1030 lbs., the 
same quantity of cream will weigh from 1020 lbs. to 
1000 lbs. or less, the weight being determined by the 
richness of the cream ; the more fat the cream contains, 
the less a certain quantity of it, e. g., a gallon, will 
weigh.^ 

2. Cream is thicker (more viscous) than milk at the 
same temperature, and more of it will adhere to the 
sides of the measuring pipette than in the case of milk. 

1 For specific gravity of cream of different richness, see table on p. 77 



Cream Testing. 77 

This is of special importance in testing very rich or 
sour cream. 

3. In case of separator cream, more or less air will 
become incorporated with the cream dnring the process 
of separation. In the ripening of cream, the fermenta- 
tion gases developed are held in the cream in the same 
way as bread dough holds the gases generated by yeast. 
In either case the weight of a certain measure of cream 
is diminished. 

87. As an illustration of the effect of the preceding 
factors on the amount of cream measured out by a Bab- 
cock 17.6 cc. pipette, the following weighings of sepa- 
rator cream are given (column 6.) Tha cream was in 
all cases fresh from the separator; it was weighed as 
delivered by the pipette into a cream test bottle (89), 
and the test proceeded with at once ; the specific gravity 
of the cream was determined by means of a picnometer 
(248). The data given are in all cases averages of sev- 
eral determinations; the samples of cream have been 
grouped according to their average fat contents.^ 



Per cent 




Weight of cream deliv- 


of fat. 


Specific gravity (17.5° C.) 


ered, grams. 


iti cream. 


(a) 


(b) 


10 


1.023 


17.9 


15 


1.012 


17.7 


20 


1.008 


17.3 


25 


1.002 


17.2 


30 


.996 


17.0 


35 


.980 


16.4 


40 


.966 


16.3 


45 


.950 


16.2 


50 


.947 


15.8 



1 For influence of condition of cream on the amount measured out 
with a 17.6 cc. pipette, see also Bartlett, Maine exp. sta., bull. 31 (S. 
S.) ; Jones, Vt. exp. sta., report 16, 101-6, and Dean, Guelph (Ont.) agr 
college, report 1906, p. 125. 



78 Testing Milk and Its Products. 

The figures in the table show plainly the variations 
in the specific gravity of cream of differ.ent richness 
and the error of making tests of cream by measuring it 
with a 17.6 cc. pipette, especially if the pipette is not 
rinsed and the washings added to the test bottle. If the 
cream to be sampled is fresh separator cream testing 
over 30 per cent., less than 17.0 grams of cream will be 
delivered into the test bottle, and the results of the 
reading will be at least one-eighteenth too low (since 
the bottles are graduated for 18 grams), or about 1.6 
per cent, too low in the case of a 30 per cent, cream. If 
the cream is sour, the error will of course be still greater. 

It should be remembered that the specific gravities 
of the cream given in the table refer to fresh separator 
cream only. Considerable air is incorporated during 
the separation, and cream of this kind is therefore lighter 
than gravity cream of corresponding fat contents. 

Babcock has calculated the specific gravity of cream 
containing different percentages of butter fat, and the 
weight of one gallon of each; see table XVI in the 
Appendix. (Hoard's Dairyman, Jan. 10, 1910.) 

88. Weighing cream for testing. For the reasons 
stated in the preceding, accurate tests of cream can 
only be made by weighing the cream into the Babcock 
test bottles.^ 

The simplest method is to weigh 9 or 18 grams of the 
samples on a small cream-weighing scale (see p. 81) into 
one of the special forms of cream-test bottles. 

1 This is recognized by a law passed by tbe Wisconsin legislature in 
1903, whicb requires cream to be weighed for testing where it is sold 
on the basis of its fat content. (Chapter 43, laws of 1903, an act to 
prescribe the standard measures for the use of the Babcock test in de- 
termining the per cent, of butter fat in milk or cream.) 



Cream Testing. 



79 



Cream-test bottles. Special forms of bottles have 
been devised for testing samples of cream by the Bab- 
cock test by Winton, Bartlett, and by various manu- 
facturers. 

89. The Winton cream bottle. The croani -test bottle 
devised by Winton,^ (fig. 32), has a neck of the usual 
length, and of sufficient width to measure 
30 or 50 per cent, of fat. The scale of 
the neck is divided into parts represent- 
ing one-half of one per cent, 
each, but readings of a quarter 
of a per cent, can easily be esti- 
mated. Such readings of 
cream tests are sufficiently ex- 
act for most commercial pur- 
poses. This form of cream bot- 
tle will be found very conven- 
ient in making tests of com- 
posite samples of cream. 

Cream test bottles of a small 
bore are greatly to be preferred 
to those with wide necks (fig. 
33), since they permit of accu- 
rate readings to a quarter of a per cent. 

Other forms of cream-test bottles which 
allow the testing of 50 or 55 per cent, cream 
have been placed on the market during late 

years by some manufacturers. These bot- 
FiG. 32a. *' "^ 

The 50% ties (so-called 9-inch bottles) have long necks 

test bottio. and require especially constructed, large and 







Fig. 32. 
The 3 0% 
cream 
bottle. 



test 



* Connecticut experiment station 
1894, p. 224. 



(New Haven), bull. 117; report 



80 



Testing Milk and Its Products. 



deep testers (see fig. 25). These machines and accom- 
panying bottles have of late been adopted for cream 
testing in many localities where farm separator cream 
is delivered to the creameries. 

90. The bulb-necked cream [^test ^bottles allow the test- 
ing of cream containing 23 or 25 per cent, of fat, when the 
usual quantity of cream (18 grams) is taken. The neck is 
graduated from to 23 per cent., and in some cases to 25 per 
cent., the graduation extending both below and above the bulb. 
This is sometimes an inconvenience, as the water must be added 
carefully so that the lower end of the column of fat 
will always come below the bulb, in the graduated 
part of the neck, and not in the bulb itself. Be- 
ginners are especially apt to lose tests when this 
bottle is first used, for the reason given. It is 
recommended to fill these bottles with the first por- 
tion of hot water to just above the bulb, so that 
one can see how much water to add the second 
t:n:e in order to bring the fat within 
the scale. 

Each division of the scale on these 
cream bottles represents two-tenths 
of one per cent, of fat, as in case 
of the milk test bottles. This form 
of bottle is no longer used to any 
extent, as it has been largely replaced 
by the different forms of the Winton 
cream-bottle. 



Fig. 33. 

The 50% 
cream test 
bottle. 




91. Scales for weighing the 
cream. When a small, delicate 
balance is used, cream can be weighed rap- 
idly into the bottles. Either of the scales 
shown in the accompanying illustrations, 
(figs. 34-35), will be found sufficiently ac- 
curate for this purpose; a small scale of 
this kind is also convenient and helpful 
in testing cheese, butter and condensed milk, in deter 



Fig. 33a. 
The 50% 9 
gram cream 
test bottle. 



Cream Testing. 



81 




Fig. 34. Scales used for weighing 
cream in the Babcock test. 



mining the strength of sulfuric acid, and in testing the 

accuracy of test bottles and pipettes. 

Cream scales similar to tJiat shown in fig. 35 permit 

the weighing of two or four samples of cream at a time 

with only one taring of 

the bottles, which great- 
ly facilitates the work of 

testing the cream. 

In testing cream by 

weight, the test bottle is 

first weighed empty, and 

again when 9 or 18 

grams of cream have been placed in it; the difference 

between the two figures gives the weight of cream taken 

for the test. If the cream 
contains less than 30 per 
cent, of fat, the regular 
milk test bottle can also 
be used for testing the 
cream, if not much more 
than 5 grams are weighed 
out ; if more cream is 
taken, or if this is richer 
than 30 per cent., it is 
advisable to use cream 
bottles. 
^j^w The operator should be 

Fig. 35. Torsion balance used for careful in weiffhinff the 
weighing creara in the Babcock test. ^ "^ 

cream not to spill it on 
the outside of the test bottle. If less than 18 grams 
of cream has been weighed into the bottle sufficient 

6 






82 



Testing Milk and Its Products. 



water is added to the balance to make the total vol- 
ume about 18 cc. The usual quantity of acid (17.5 cc.) 
is then added, and the test completed in the ordi- 
nary manner. The reading of the amount of fat in 
the neck of the test bottle will not show the correct 
per cent, of fat in the cream unless exactly 18 grams are 
weighed out. If less than this weight was taken the 
per cent, of fat in the cream tested is obtained by multi- 
plying, the reading by 18, and dividing the product by 
the weight of cream taken. 

Example: Weight of cream tested, 5.2 grams; reading of col- 
umn of fat ^) 9.8, ^) 9.7, average 9.75; per cent, of fat in the cream 

-^^-33.75. 

It is very convenient to weigh out 18 grams of cream 

(or 9 grams) so that the 
readings may be taken di- 
rectly from the neck of the 
bottle. The smaller the quan- 
tity of cream taken for a 
sample, the greater is the 
error introduced by inaccu- 
rate weighings or readings. 
The result is rendered more 
accurate if two or three tests 
of a sample are made, and 
the readings averaged. 

91a. The hydrostatic bal- 
ance is a convenient device 
for weighing cream and 
other dairy products to be 
tested by the Babcock test 

Fig. viSa. The Wisconsin by- /• n or \ i mi • i i 

drostatic cream balance. (see fio:. SdH).^ ihlS balance 




1 Wisconsin exp. station, bull. 195. 



Cream Testing. 83 

is built on the same principle as a lactometer : it is pro- 
vided with a pan on the top of the stem, on which the 
test bottles and the weights are placed. When put into 
water the instrument is balanced to a certain point 
with empty test bottles and weights on the pan ; the 
weights are then removed and sufficient cream added 
to the test bottle by means of a pipette to sink it to 
the same point as before. 

The special advantages of the balance are that there 
are no bearings to rust and become dull; it is durable, 
inexpensive and sensitive, and with careful handling 
will remain sensitive indefinitely. The balance can be 
made large enough to weigh a number of bottles at a 
time, as is the case with some of the cream scales on 
the market. 

92. Measuring cream for testing. Where a special 
cream scale or a small balance is not available, fairly 
satisfactory results may be obtained with cream of low 
or average quality by measuring out the sample with 
a 17.6 pipette and correcting the results as indicated 
below. One of the cream test bottles or a common milk 
test bottle may be used for this purpose. The table 
en p. 77 sliows that a 17.6 cc. pipette, in the case of 
cream fresh from the separator, containing less than 
25 per cent, of fat, will deliver only 17.2 grams of 
cream, that is, the results will be •'^--'^=1.1 per cent, too 

' ^ 18 ^ 

low. In the same way in case of 40 per cent, cream, 
only 16.3 grams of cream would be delivered, and the 
results therefore 3.8 per cent, too low. Wlien the cream 
has been ripened or is thick, less cream would be deliv- 
ered than the amounts given, and the error introduced 
by measuring out the samples correspondingly increased. 



84 Testing Milk and Its Pjvducts. 

A table of correction for testing such cream by meas- 
uring the samples has been prepared by Prof. Eckles, 
formerly of Iowa experiment station.^ 

Approximately correct results may be obtained in 
testing thin cream by using an 18 cc. measuring pipette ; 
to avoid the expense and trouble of using two different 
pipettes, one for milk and one for cream, a pipette with 
two marks on the stem, at 17.6 cc. and 18 cc, has been 
placed on the market, the former mark being used when 
milk is tested, and the latter for cream. It should be 
borne in mind, however, that such pipettes can only be 
used in the case of sweet cream of average richness, 
and will then give only approximately correct results 

93. Use of milk test bottles. Cream may be tested 
by emptying a 17.6 cc. pipetteful into two or more milk 
test bottles, dividing the sample about equally between 
the bottles and filling the pipette with water once or 
twice, which is then in turn divided about equally be- 
tween the test bottles ; the per cent, of fat in the 
cream is found by adding the readings obtained in 
each of the bottles. The cream and the water must be 
mixed before the acid is added. 



^ Press bull, dated Au??ust, 1901. Some creameries heat the samples 
of cream in a water bath to about 140° F. before the test samples are 
measured out by means of a 17.6 cc. pipette. This increases the fluidity 
of the cream and causes less to adhere to the pipette. The Vermont ex- 
periment station (report 16. pp. 191-6) found in examining this method 
that it did not yield satisfactory results in the case of cream of dif- 
ferent richness and recommends that cream be weighed when accurate 
tests are desired. 

Professor Spillman (Bull. 32 of Washington experiment station) rec- 
ommends the use of a 17.6 cc. pipette for testing cream, the results 
obtained being corrected by a certain per cent., as shown in a table 
given in the bulletin. The table is based on the figures given on p. 77 
of this book, and is therefore only applicable to fresh separator cream. 



Cream Testing. 85 

This method does away with tlie error incident to the 
adhesion of cream to the side of the pipette, but not 
with that due to the low specific gravity of the cream^ 
and the results obtained will therefore be too low. 

The dilution of the cream with water in the test bot- 
tles not only makes it possible to bring into the bottle 
all the cream measured out, but also insures a clear test. 
If ordinary cream is mixed with the usual quantity 
of sulfuric acid used in the Babcock test, a dark-colored 
fat will generally be obtained, while the cream diluted 
with an equal or twice its volume of water, when mixed 
with the ordinary amount of acid, wall give a light yel- 
low, clear column of fat, which will allow of a very 
distinct and sharp reading. 

The number of bottles to be used for testing a sam- 
ple of cream by this method must be regulated by the 
richness of the cream. If the sample probably contains 
20 per cent, or more, a pipetteful should be divided 
about equally betw^een three milk test bottles, and two- 
thirds of a pipetteful of water is added to each bottle. 
If the cream contains less than 20 per cent, of fat, it 
will only be necessary to use two. milk test bottles, divid- 
ing the pipetteful between these, and adding one-half 
of a pipetteful of water to each bottle. 

By using cream test bottles (89), more accurate tests 
may be obtained in case of cream containing as much 
as 25 per cent, of fat, by dividing one pipetteful be- 
tween two bottles, rinsing half a pipette of water into 
each one, than by adding all the cream to one bottle 
without rinsing the pipette, for reasons apparent from 
what has been said in the preceding. 



86 



Testing Milk and Its Products. 



94. Use of a 5 cc. pipette. When the cream is in good con- 
dition for sampling, satisfactory results can also be obtained by 
the use of a 5 *ic. pipette, provided great care is taken in mix- 
ing the cream before sampling; 5 cc. of cream are measured into 
a milk test bottle, and two pipettefuls of water are added. In 
this way all the cream in the pipette is easily rinsed into the 

test bottle. The readings multiplied by ^^^ =3.6 will give the 
per cent, of fat in the cream. If the specific gravity of the 
cream tested varies appreciably from 1, corrections should be 
made accordingly; e. g., if the specific gravity is 1.02, the fac- 
tor should read '^ — oro. ,•* nn is 



18 

5X1.0;^ 



=3.53; if .95, ^A- =3.79, etc. 

' ' 5X.S5 ' 



-cC 



95. Proper readings of cream tests. The accom- 
panying illustration (fig. 36), shows the proper method 
of reading the fat column in cream 
tests; readings are taken from a to c, 
not to b or to d, when readings are 
made at 140° F.^ 

No special precautions other than 
those required in testing milk have been 
found necessary in testing cream, ex- 
cept that it is sometimes advisable not 
to whirl the test bottles in the centri- 
fuge at once after mixing, but to let the 
cream-acid mixture stand for a while, 
until it turns dark colored. At first, 
the mixture of cream and acid is much 
lighter colored than that of milk and 
acid, owing to the smaller proportion of 
in^/he^ ?eok^of™a solids not fat Contained in the cream, 
ing^shouid be made The liquid beneath the fat in a com- 
6^0? to d. ^' °^ ° pleted test of cream is sometimes milky 



a- 



Fig. 36. Measur- 



1 The size of the meniscus is magnified in this cut. A study of the 
mensicus formed in bottles with narrow or wide necks, and its bearing 



Cream Testing. 87 

and the fat appears white and cloudy, making an exact 
reading difficult. Such defects can usually be over- 
come by placing the test bottles in hot water for about 
ten minutes previous to the whirling, or by allowing the 
fat to crystallize (which is done by cooling the bottles 
in cold water after the last whirling) and remelting 
it by placing the bottles in hot water. 

The error due to the expansion of the fat in case of 
excessively hot turbine testers having no openings in 
the cover as mentioned on p. 36, is especially noticeable 
in cream testing, where it may amount to one per cent. 
or more. In order to obtain correct results with such 
testers, the hot cream test bottles must be placed in 
water at about 140° F. for some minutes before the 
results are read off. 

The subject of different methods of reading cream 
tests have been studied by Webster and Gray,^ who 
conclude that correct results are obtained by taking 
readings at 120° F., from the bottom to the extreme 
top of the fat column, deducting four-fifths of the 
depth of the meniscus from this result and adding .2 
per cent, to the figure thus obtained. 

96. Eliminating the meniscus in cream tests. The 
uncertainty concerning the exact point at which the 
meniscus of the fat column should be read in cream 
tests has been removed by the use of certain liquids 
which do not mix with fat but when dropped on top of 

on the results of cream tests is given in bulletin 58, Bur. An. Ind., 
U. S. Dept. of Agriculture, vrhere a discussion of the influence of dif- 
ferent temperatures on readings of cream tests will also be found (see 
96). 

* Bull. 58, Bur. An. Ind., U. S. Dept. of Agriculture. See also Mass. 
rept., 1909, p. 142. 



88 



Testing Milk and Its Products. 



the fat column change the curved surface of the menis- 
cus into a straight line. Amyl alcohol, fat-saturated 
alcohol and glymol have been suggested for this pur- 
pose. 

Amyl alcohol colored red by fuchsin was suggested 
by Eckles.^ This may dissolve some of the fat and thus 
cause a slightly low reading. Fat-saturated alcohol'- 
largely overcomes this objection. It is made by adding 
about a teaspoonful of butter to six ounces of dena- 
tured or wood alcohol in a stoppered bottle. This is 
warmed slightly and shaken until the alcohol does not 
dissolve any more of the fat. A small amount of 

coloring matter may be added to 
this solution to further facilitate 
the reading. The use of glymol^ or 
white mineral typewl*iter and sew- 
ing machine oil was suggested by 
Ilunziker for reading cream tests, 
after an exhaustive study of the 
subject, (jlymol may be colored 
with alkanet root which can be ob- 
tained from a druggist. One ounce 
of alkanet root will color one quart 
of glymol; this is done by placing 
a small cheese cloth bag filled with 
the alkanet root in the bottle of 
glymol for one or two days. 
A convenient way of adding alcohol, glymol, etc., to 
the fat column after completing a test is to insert a 

1 N. y. Produce Review, Aug. 8, 1908. 

2 Wis. Expt. Sta. Bui. 195, p. 6. 

•Purdue, Ind., Expt. Sta. Bui. 145, vol. XV, p. 593. 




Fig. 26a. Showing the 
use of fat-saturated 
alcohol, glymol. etc., 
for eliminating the 
meniscus in cream 
tests. 



Cream Testing. 89 

glass tube through a cork or stopper of a bottle con- 
taining the liquid and by placing a finger on the top 
of the tube a small portion may be transferred from 
the bottle to the top of the fat column. By the use of 
either of the liquids mentioned the meniscus in cream 
tests disappears, giving a straight line at the top as 
well as the bottom of the fat column and thus making 
it possible to obtain exact readings of the per cent, of 
fat in any sample of cream. 



Questions. 

* 

1. Give three reasons for weighing cream for testing. 

2. How does the richness of the cream influence its weight! 

3. What is the weight of one gallon of cream testing 10, 30, 
or 50% fat? 

4. Describe at least three forms of cream test bottles. 

5. What is the use of a bulb in the cream bottle? 

6. Between what points should the cream fat column be read? 

7. If cream was erroneously weighed into a test bottle as 9.3 
gr. instead of 10 gr., what error would this cause on a sample 
testing 33% fat? 

8. Mention a few important points in the construction of & 
cream test bottle. 

9. If 12.5 gr. cream give a reading of 18.5, what is the cor- 
rect test of the sample? 

10. If 7.2 gr. of cream give a reading of 6.4, what is the cor- 
rect test of the sample? 

11. If the fat in a cream test is read as 28% at a temperature 
of ISO" F., what is the correct test? 

12. If at the end of a full day's run 4,280 lbs. of milk had 
been received, testing 3.95 per cent., and 535 lbs. of cream test- 
ing 34.5 per cent, fat; how much fat (a) in the whole milk; 
(b) in the cream; (c) in the skim milkf (d) what would be 
the test of the skim milk, (e) how many pounds of skim milk 
would there be; and (f) what would be the per cent, of cream 
fro mthe milk? 



CHAPTER V. 

BABCOCK TEST FOR OTHER MILK PRODUCTS. 

97. Skim milk. Each division on the scale of the 
neck of the regular Babcock test bottle represents two- 
tenths of one per cent. (44). When a sample of skim 
milk or butter milk containing less than this per cent, 
of fat is tested, the estimated amount is expressed by 
different operators as one-tenth, a trace, one-tenth trace, 
or one- to five-hundredths of one per cent. Gravimetric 
chemical analyses of skim milk have, however, shown 
that samples which give only a few small drops of fat 
floating on the water in the neck of the test bottle, or 
adhering to the side of the neck, generally contain 
one-tenth of one per cent, of fat, and often more. Samples 
of skim milk containing much less than one-tenth of a 
per cent, of fat are very rare, and it is doubtful whether 
a sample of separator skim milk representing a run 
of, say 5000 lbs. of milk, will ever show less than 
five-hundredths of one per cent, of fat. Under ordi- 
nary factory conditions, few separators will deliver 
skim milk contain! Dg under one-tenth of one per cent, 
of fat, when the sample is taken from the whole day's 
run. This must be considered a satisfactory separation.' 

1 For comparative analyses of separator skim milk by the gravi- 
metric method and by the Babcock test, see Wis. exp. station bull. 52 
and rep. XVII, p. 81; Conn. (Storrs) exp. station, bull. 40; Utah exp. 
station, bull. 96. See also, Woll, Testing: Skim Milk by Babcock Test, 
in Country Gentleman, April 26, 1902. The results obtained by the use 
of the Gottlieb method have shown that ether-extraction methods, as 



Bahcock Test for other Milk Products. 91 

98. The reason why the Babcock test fails to show all 
the fat present in skim milk must be sought in one or 
two causes: a trace of fat may be dissolved by the sul- 
furic acid, or owing to the minuteness of the fat glob- 
ules of such milk they are not brought together in 
the neck of the bottles at the speed used with the Bab- 
cock test. The latter cause, is the more likely explana- 
tion. If a drop of the dark liquid obtained in a Bab- 
cock bottle from a test of whole milk be placed on a 
slide under the microscope, it will be seen that a fair 
number of very minute fat globules are found in the 
liquid. These globules are not brought into the column 
of fat in the neck of the bottle by the centrifugal force 
exerted in the Babcock test, even if the bottles are 
whirled in a turbine tester in which they are heated 
to 200° F, or higher (see 71) ; the loss of the fat con- 
tained in these fine globules is compensated for, in the 
testing of whole milk, by a liberal reading of the fat 
column, the reading being taken from the bottom of 
the fat to the top of the upper meniscus (see p. 35) ; 
in some separator skim milk, on the* other hand, not 
enough fat remains to completely fill the neck, and the 
reading must therefore be increased by at least five- 
hundredths of one per cent. 

It follows from what has been said that tests of skim 
milk showing no fat in the neck of the test bottles on 
completion of the test, generally indicate inefficient 
work of the centrifugal tester or of the operator, or of 

well as the Babcock test, give too low results with dairy by-products 
low In fat, like skim milk, butter-milk, etc. The Gottlieb method for 
this reason has been adopted by European chemists as a standard for 
analysis of these products. (See 254). 



92 



Testing Milk and Its Products. 



both. The test should be repeated in such cases, using 
more acid and whirling for full five minutes. Sepa- 
rator skim milk should be allowed to stand 10 to 15 min- 
utes before the sample is taken so as to allow the air 
to escape. 

In order to bring as much fat as possible into the 
neck of the bottles in testing skim milk, it is advisable 
to add somewhat more acid than when 
whole milk is tested, viz., about 20 cc, 
and to whirl the bottles at full speed for 
at least five minutes, keeping the tester as 
hot as possible the whole time.^ The read- 
ings must be taken as soon as the whirl- 
ing is completed, since owing to the con- 
traction of the liquid by cooling, the fat 
will otherwise adhere to the inside of the 
neck of the test bottle as a film of grease 
which cannot be measured by the scale. 

99. The double-necked test bottle, 
(fig. 37), suggested by one of us,- is made 
especially for measuring small quantities 
of fat and gives fairly satisfactory results 
in testing skim milk and butter milk. 
Each division of the scale in these bottles 
represents five-hundredths of one per -piG. 37. The 
cent., and the marks are so far apart that ^kim^^muk^ \o?- 

J.1 ^^ £ I. ^ i, '^ ..tie (sometimes 

the small lat column can be easily esti- called the ohi- 
mated to single hundredths of one pei bottle). 

1 See Wis. exp. station, report 17, p. 81. 

* First constructed by Mr, J. J. Nussbaumer, of Illinois; now manu- 
factured by various firros. 



Bahcock Test for other Milk Products. 93 

cent. In the first forms, now out of use, the neck was 
graduated to hundredths of one per cent. 

The value of the divisions of the scale on the double- 
necked test bottles has been a subject of considerable 
discussion, and various opinions have been expressed 
whether they show one-tenth or one-twentieth (.05) of 
one per cent, of fat. By calibration with mercury the 
value of the divisions will be found to be .05, or one- 
twentieth, of one per cent., but as shown above, the re- 
sults obtained in using the bottles for separator skim 
milk generally come at least .05 per cent, too low, so 
that, practically speaking, each division may be taken 
to show one-tenth of one per cent., if the fat fills only 
one division of the scale or less.^ 

The double-necked bottle is very convenient for the 
testing of separator skim milk, thin butter milk and 
whey. The milk, acid and water are added to the bottle 
through the filling-tube; the mixing' of milk and acid 
must be done with great care, so that none of the con- 
tents is forced into the fine measuring tube and lost; it 
is best to add half of the acid first and mix it with the 
milk, and then add the rest. When the fat is in the 
lower .end of the measuring tube, it can be forced into 
the scale by pressing with the finger on the top of the 
side tube. 

In placing the double-necked bottles in the tester they 
should be put with the filling tube toward the center, so 
as to avoid any of the fat being caught between this 
tube and the side of the bottle when it resumes a verti- 
cal position. 

1 Wis. exp. station, bull. 52 ; Tenna. exp. ^tation. report 1896, p. 221. 



94 



Testing Milk and Its Products. 



This test bottle is more fragile and expensive than 
the ordinary Babcock bottles, and must be carefully 
handled; it is now generally made of heavier glass 
than formerly, and this form is to be highly recom- 
mended.^ 

100. The double-size skim milk bottle which was the 
first one recommended for the testing of skim milk, is of no 
particular value. It is difiBcult to obtain a thorough mixture of 
the milk and the acid in these bottles, and the tests invariably 
come too low, more so than with the regular Babcock bottles or 
double-necked skim milk bottles, for reasons 
that are readily seen. 

loi. Buttermilk and whey. The 

testing of buttermilk by the Babcock 
test offers no special difficulties if the 
special directions for testing skim milk 
are followed ; what has been said in re- 
gard to tests of separator skim milk is 
equally true in case of this by-product. 
Whey contains only a small quantity 
of solids not fat, viz., less than 7 per 
cent. (27), and the mixing with acid 
and the solution of the whey solids 
therein is therefore readily accom- 
plished; the acid solution is of a light 
reddish color, .turning black but very 
slowly. 

I02. Butter. Butter is not so easily tested as other 
dairy products, both because of the difficulties in ob- 
taining a fair sample, and on account of the high per- 
centage of fat it contains. Butter is a mechanical mix- 




Fui. '68. 

The double-bore 

skim milk bottle. 



1 A double-becked copper test bottle with a detachable graduated 
glass neck was designed and tried by one of us a few years ago, but it 
was not found to possess any special advantage over the glass bottle. 



Bahcock Test for other Milk Products. 95 

ture of water, curd, and salt, with butter-fat; and the 
water or brine is so easily pressed out that great care 
must be taken to get the same amount of water in the 
small portion to be tested as exists in the lot of butter 
sampled. 

Sampling butter. Small portions of butter are taken 
with a butter trier or a knife from different parts of 
the tub, package, or churning of butter to be tested. 
These small portions (preferably about 200 grams in 
all) are placed in a wide-necked bottle or jar which is 
securely stoppered and placed in warm water until the 
butter melts. The jar is then shaken vigorously in order 
to obtain a thorough mixing of the various components 
of the butter, and placed in cold water. As the butter 
cools, the jar must be shaken repeatedly until the butter 
either solidifies or becomes of a thick creamy consist- 
ency. From this sample small portions may be taken 
for testing. 

It is not always necessary to prepare a sample of 
butter for testing in the manner described. If the but- 
ter contains no loose drops of brine on the freshly-cut 
surface, a sample for testing can be taken directly from 
the package. The operator must use his judgment in 
regard to the necessity of preparing a .special sample in 
each case. 

Scales for weighing butter. In testing butter it is 
necessary to weigh the amount taken for a test very 
accurately. Scales sensitive to less than .05 gram should 
be used, as a difference of .1 gram in weight has a value 
of 1.0 per cent, in the result when 10 grams of butter 
are tested. Slow-working scales with rusted bearings 
are worthless for testing butter. The scales should 



96 Testing Milk and Its Products. 

always be balanced before being used and the weights 
kept bright and clean. 

Carelessness in weighing may be the cause of very 
inaccurate results, and the importance of a sensitive 
scale cannot be over-estimated. Scales with a graduated 
side beam are preferable to those that require the use 
of small weights. Scales sensitive to .01 gram are now 
on the market, which permit of 20 to 50 grams of butter 
being weighed out for testing.^ 

103. Fat in butter. The Babcock test can be used 
with a fair degree of accuracy for estimating the per 
cent, of fat in butter, by weighing 9 grams of butter 
into a test bottle graduated to measure 50 per cent. fat. 
About 10 cc. of hot water is added to the butter, and 
17.5 cc. of sulfuric acid of one-half the strength used in 
milk testing. Mix the butter and acid until the curd 
is all dissolved, add hot water to bring the fat into 
the neck of the test bottle and whirl in a centrifuge. 
When a clear separation of the fat is obtained the test 
bottle is placed in water of 140° F. up to near the top 
of the neck and after standing a few minutes in this 
water the fat column is read off ; the reading multiplied 
by 2 gives the per cent, of fat. 

Accurate results can only be obtained by taking great 
care in all the manipulations, especially in weighing the 
butter and in reading the fat at the proper tempera- 
ture. Small errors in making tests have a marked influ- 
ence on the results, because the butter fat is such a 
large per cent, of the butter. Tests should always be 
made in duplicate.^ 

1 See bull. 154, Wisconsin exp. sta., p. 10. 

2 Special bottles for testing butter for its fat content have been put 



Bahcock Test for other Milk Products. 97 

104. Cheese. Cheese can be easily tested by the Bab- 
cock test if a small scale (fig. 34) is at hand for weigh- 
ing the sample; the results obtained will furnish accu- 
rate information as to the amount of fat in the cheese, 
provided good judgment and exactness are used in 
sampling and weighing the cheese. The following 
method of sampling cheese is recommended.^ 

"Where the cheese can be cut, a narrow wedge reaching from 
the edge to the center of the cheese will more nearly represent 
the average composition of the cheese than any other sample. 
This may be cut quite fine, with care to avoid evaporation of 
water, and the portion for analysis taken from the mixed mass. 
When the sample is taken with a cheese trier, a plug taken per- 
pendicular to the surface, one-third of the distance from the 
edge to the center of the cheese, will more nearly represent the 
average composition than any other. The plug should either 
reach entirely through or only half way through the cheese. 

**For inspection purposes the rind may be rejected, but for 
investigations, where the absolute quantity of fat in the cheese 
is required, the rind should be included in the sample. It is 
well, when admissible, to take two or three plugs on different 
sides of the cheese and after splitting them lengthwise with a 
sharp knife, take portions of each for the test." 

105. When a satisfactory sample of the cheese has 
been obtained, about 5 grams are weighed into a milk 
test bottle, or a larger quantity (say 9 grams) may be 
used with a cream tes't bottle. The test bottle is first 
weighed empty, and again after the pieces of cheese have 
been added. About 15 cc. of hot water is added to the 
cheese in the test bottle, and this is shaken occasionally 
until the cheese softens and forms a creamy emulsion 



on the market, e. g., the Wagner Butter Test Bottle and the form sug 
gested by H. R. Wright, given in the 18th report of the Iowa State 
Dairy Commissioner, 1904, p. 40. 
1 U. S. Dept. of Agriculture, Chemical Division, bull. 4G, p. 37. 

7 



98 Testing Milk and Its Products. 

with the water. A few cc. of acid will aid in this mixing 
and disintegration, the process being hastened by placing 
the bottles in tepid water. When all lumps of cheese 
have disappeared in the liquid, the full amount of acid 
is added, and the test completed in the ordinary man- 
ner.^ 

The per cent, of fat in the cheese is obtained by mul- 
tiplying the reading of the fat column by 18 and divid- 
ing the product by the weight of cheese. The weighing 
of the cheese and the reading of the fat must be done 
very carefully, since any error introduced is more than 
trebled in calculating the per cent, of fat in the cheese. 

io6. Condensed milk. The per cent, of fat in un- 
sweetened condensed milk can be obtained by weighing 
about 9 grams into a test bottle and proceeding in ex- 
actly the same way as given under testing of cheese. 
It is not necessary to warm the condensed milk in the 
test bottles, since this is readily dissolved in water. 
Enough water should be added to make the total volume 
of liquid in the bottles 15 to 18 cc. 

If a scale is not available for weighing the sample, 
fairly accurate results may be obtained by diluting the 
condensed milk with water (1:3), and completing the 
test in the ordinary manner. When this is done, the 
results must be corrected for the dilution Avhich the 
sample received. 

Ilunziker- recommends adding hot, dilute sulfuric 
acid solution after the first whirling, in the analysis of 
unsweetened condensed milk (sulfuric acid and water, 

1 See also Sammis, .Tourn. Ind. and Eng. Chem., I, p. 604. 

2 Ind. expt. sta., bull. 134. 



Bahcock Test for other Milk Products. 99 

1:1). He finds that this aids in giving a clear separa- 
tion of the fat and obtaining satisfactory results.^ 

107. Sweetened condensed milk. The testing of 
sweetened condensed milk presents peculiar difficulties, 
whether it is to be tested by the Babcock test or by 
chemical analysis. It may, however, be readily tested 
by the Babcock test by introducing certain changes in 
the manipulation of the test, as worked out by one of 
us." A brief description of the method of analysis 
adopted is here given. 

About sixty grams of condensed milk are weighed 
into a 200 cc. graduated flask, to this 100 cc. of w^ater 
are added and the solution of the condensed milk ef- 
fected. The flask is then filled to the mark with water 
and after mixing thoroughly, a 17.6 pipette full of 
measured into a Babcock test bottle. About three cc. 
of the sulfuric acid commonly used for testing milk are 
then added and the milk and acid mixed by shaking the 
bottle vigorously. The milk is curdled by the acid, and 
the curd and w^hey separated somewhat. In order to 
make this separation complete and to compact the curd 
into a firm lump, the test bottle is whirled for about six 
minutes at a rather high speed (1,000 rev.) in a steam- 
heated turbine tester. 

The chamber in which the bottles are whirled ought 
to be heated to about 200° F. This ean be done either 
by the turbine exhaust steam which leaks into the test- 

1 For analysis of unsweetened condensed milk, see also .Jr. Ind. and 
En?. Chem.. 1913, pp. 131 and 168. Good results may be secured by 
adding 3 cc. of a mixture of equal parts of amyl alcohol and C. P. 
hydrochloric acid to the milk, then 10 cc. of C. P. sulfuric acid, and 
proceeding as given above (Araott). 

2 Wis. exp. station, report XVII, pp. 80-80. 



100 Testing Milk and Its Products. 

bottle chamber of some machines, or by means of a 
valve and pipe which will allow steam to be turned di- 
rectly into the test bottle chamber. After this first 
whirling the bottles are taken from the tester 
and by being careful not to break the lump of curd 
nearly all the whey or sugar solution can be poured out 
of the neck. Ten cc. of water are then poured into the 
test bottle and the curd is shaken up with it so as to 
wash out more of the sugar. Three cc. of acid are now 
added as before and the test bottle whirled a second 
time. The whey is again decanted and this second 
washing removes so much of the sugar that what re- 
mains will not interfere with testing in the usual way. 
The curd remaining in the bottle after the second wash- 
ing is shaken up with ten cc. of water; the water-emul- 
sion of the curd is then cooled; the usual amount, 17.5 
cc, of sulfuric acid is added, and the test completed in 
the same way as when milk is tested. The amount of fat 
obtained in the neck of the test bottle is calculated to 
the weight of condensed milk taken.^ 

io8. Ice cream. ]\Iethods for determining the per 
cent, of fat in ice cream have been worked out by 
Holm,- Howard^ and others. Holm recommends the 
use of a mixture of equal parts of hydrochloric and 
glacial acetic acid, in the place of sulfuric acid, as the 

1 The GottUeb method gives very satisfactory results with both cheese 
and condensed milk (see 254). See also Jr. Ind. and Eng. Chem., 
1912, p. 672. For method of analysis of desiccated milk, milk powder, 
etc., see ibid., 1912, p. 544. 

2 Report Dept. of Health, City of Chicago, 1900, p. 50. 

3 Journ. Am. Chem. Soc, 1907, p. 16. Methods of analysis of ice 
cream have also been proposed by White, (Penna. exp. sta., rept. 1910, 
p. 243), Baird, (N. Y. Prod. Rev., Feby. 26, 1913), and Halvorsen, 
(Jr. Ind. and Eng. Chem., 5 (1913), p. 403). 



The Lactometer and Its Application. 101 

latter is likely to char the sugar in the ice cream, thus 
giving difficulty in reading the results. Nine grams of 
either the frozen or melted sample are weighed into a 
Babcock milk bottle, which is then filled almost to the 
neck with the mixture of the two acids given. This is 
heated for a few minutes until black, when the bottle is 
whirled in the tester and water added to bring the fat 
column within the graduations of the neck, as in the 
regular Babcock test. The reading multiplied by two 
gives the per cent, of fat in the ice cream.^ 



Questions. 

1. Why is it diflScnlt to get accurate tests of skim milk by 
the Babcock test? 

2. Mention at least three precautions that should be taken 
in testing skim milk. 

3. Should more acid be used for full milk than for skim 
milk, or more for skim milk than for whey? Why? 

4. How much fat is probably present in a sample of skim 
milk which shows no fat on being tested in a skim milk bottle! 

5. What per cent, of fat does each division of a double- 
necked skimmilk test bottle represent? 

6. How can (a) butter, (b) cheese, (c) unsweetened and 
sweetened condensed milk be tested with the Babcock test? 

7. If 8.4 gr. cheese give a reading of 12.2% on the neck of a 
test bottle, what per cent, of fat does the cheese contain? 

8. What Is the per cent, of fat in a sample of cheese, of 
which 4.2 grams contained enough fat to fill the space in the 
neck of a Babcock milk test bottle from 1.7 to 9.5 mark? 

9. How can the per cent, of fat in ice cream be determined? 



1 An apparatus for determining the amount of overrun (214) in the 
manufacture of ice cream has been devised by G. H. Benkendorf of 
Wis. exp. station (see bull. 239 of the station). 



CHAPTER VI. 

THE LACTOMETER AND ITS APPLICATION. 

109. The lactcmeter is used for determining the spe- 
cific gravity of milk. The term specific gravity means 
the weight of a certain volume of a solid or a liquid 
substance compared with the weight of the same vol- 
ume of water at 4° C. (39.2° Fahr.) ; for gases the 
standard of comparison is air or hydrogen. If the milk 
which a can will hold weighs exactly 103.2 lbs., this can 
will hold a smaller weight of water, say 100 lbs., as milk 
is heavier than water; the specific gravity of this milk 
will then be 1 o-^-a —1.032. 

1 u 

The specific gravity of normal cow's milk will vary 
in different samples between 1.029 and 1.035 at 60° F., 
the average being about 1.032. The specific gravity of 
skim milk is about 1.036-1.038, and of sweet cream 1.01 
to .95, according to the per cent, oi fat contained there- 
in; average specific gravity 1.0 (see p. 77).^ 

The lactometer enables us to determine rapidly the 
relative weight of milk and water. Its application rests 
on well-known laws of physics : When a body floats in 
a liquid, the weight of the amount of liquid which it 
replaces is equal to the weight of the body. It will sink 
further into a light liquid than into a heavy one, be- 

1 Since a gallon of water weighs 8.34 lbs., 1 gal. of milk will weigh 
S.34X1.<^32 or 8.6 lbs.; 1 gal. of skim milk, 8.7 lbs., and 1 gal. of 
cream from 8.1 to 8.5 lbs., according to its richness. (See Table XVI, 
Appendix.) 



The Lactometer and Its Application. 



103 



cause a larger volume of the former will 
be required to equal the weight of the 
body. A lactometer will therefore sink 
deeper into milk of a low specific grav- 
ity than into milk of a high specific 
gravity. 

no. The Quevenne lactometer. 
This instrument (fig. 39), consists of 
a hollow cylinder weighted by means of 
mercury or fine shot so that it will float 
in milk in an upright position, and pro- 
vided with a narrow stem at its upper 
end, inside of which is found a gradu- 
ated paper scale. In the better forms, 
like the Quevenne lactometer shown in 
the figure, a thermometer is melted into 
the cylinder, with its bulb at the lower 
end of the lactometer and its stem ris- 
ing above the lactometer scale. 

The scale of the Quevenne lactometer 
is marked at 15 and 40, and divided into 
25 equal parts, with figures at each five 
divisions of the scale. The single divis- 
ions are called degrees. The 15-degree 
mark is placed at the point to which the 
lactometer will sink when lowered into^ 
a liquid of a specific gravity of 1.015, 
and the 40-degree mark at the point to 
which it will sink when placed in a 
liquid of a specific gravity of 1.040. 





Fig. 39. 
Quevenne lacto- 
meter floating in 
milk in a tin cylin- 
der (115). 



104 Testing Milk and Its Products. 

The specific gravity is changed to lactometer degrees 
by multiplying by 1000 and subtracting 1000 from the 
product. 

Example: Given, the specific gravity of a sample of milk, 
1.0345; corresponding lactometer degree, 1.0345X1000 — 1000= 
34.5. 

Conversely, if the lactometer degree is known, the 

corresponding specific gravity is found by dividing by 

1000 and adding 1 to the quotient (34:.5-^-1000=.0345; 

.0345+1=1.0345). 

111. Influence of temperature. Like most liquids, 
milk will expand on being warmed, and the same vol- 
ume will, therefore, weigh less when warm than before ; 
that is, its specific gravity will be decreased. It follows 
then that a lactometer is only correct for the tempera- 
ture at which it is standardized. If a lactometer sinks 
to the 32-mark in a sample of milk of a temperature of 
60° F., it will only sink to, say 33, if the temperature 
of the milk is 50° F., and will sink farther down, e. g., 
to 31, if the temperature is 70° F. Lactometers are 
generally standardized at 60° F., and to show the cor- 
rect specific gravity the milk to be tested should first be 
warmed (or cooled, as the case may be) to exactly 
60° F. 

112. Correction tables. Tables have been constructed 
for correcting errors in lactometer readings due to 
differences in temperature. As the fat content of a 
sample of milk has a marked influence on its specific 
gravity at different temperatures, the co-efficient of 
expansion of fat differing greatly from that of the 
milk serum, the table cannot give absolutely accurate 



The Lactometer and Its Application. 105 

corrections for all kinds of milk, whether rich or poor. 
But the error introduced by the use of one table for all 
kinds of whole milk within a comparatively small 
range of temperature, like ten degrees above or below 
60°, is too small to have any importance outside of 
exact scientific work, and in such, the specific gravity 
is always determined by means of a picnometer or a 
specific-gravity bottle (248), at the exact temperature 
at which this has been calibrated. In taking the spe- 
cific gravity of a sample of milk by means of a lacto- 
meter, the milk is always warmed or cooled so that its 
temperature does not vary ten degrees either way from 
60° F. 

113. The temperature correction table for whole milk, 
given in the Appendix shows that if, e. g., the specific 
gravity of a sample of milk taken at 68° F. was found 
to be 1.034, its specific gravity would be 1.0352 if the 
milk was cooled down to 60°. If the specific gravity 
given was found at a temperature of 51°, the corrected 
specific gravity of the milk would be 1.0329. 

In practical work in factories or at the farm, suffi- 
ciently accurate temperature corrections may generally 
be made by adding .1 to the lactometer reading for 
each degree above 60° F., and subtracting .1 for each 
degree below 60° ; e. g., if the reading at 64° is 32.5 
it will be about 32.5+.4=32.9 at 60° F. ; and 34.0 at 
52° F. will be about 34.0— .8=33.2 at 60° F. The table 
in the Appendix gives 33.0 as the corrected figure in 
both cases. 

The scale of the thermometer in the lactometer should 
be placed above the lactometer scale so that the tern- 



106 Testi7ig Milk and Its Products. 

perature may be read without taking the lactometer out 
of the milk ; this will give more correct results and will 
facilitate the reading. 

114. N. Y. Board of Health lactometer. In the East and 
among city milk inspectors generally, the so-called New York 
Board of Health lactometer is often used. This does not give 
the specific gravity of the milk directly, as is the case with the 
Quevenne lactometer; but the scale is divided into 120 equal 
parts, known as Board of Health degrees, the mark 100 being 
placed at the point to which the lactometer sinks when lowered 
into milk of a specific gravity of 1.029 (at 60° F.) ; this is con- 
sidered the lowest limit for the specific gravity of normal cow's 
milk. The zero mark on the scale shows the point to which the 
lactometer will sink in water j the distance between these two 
marks is divided into 100 equal parts, and the scale is contin- 
ued below the 100 mark to 120. As 100" on the Board of Health 
lactometer corresponds to 29° on the Quevenne lactometer, the 
zero mark showing in either case a specific gravity of 1, the 
degrees on the former lactometer may easily be changed into 
Quevenne lactometer degrees by multiplying by .29. To fur- 
ther aid in this transposition, Table III is given in the Appen- 
dix, showing the readings of the two scales between 60° and 
120° on the Board of Health lactometer. 

The temperature correction for Board of Health lactometers 
is as follows: for each degree of temperature above 60° F. .3 is 
added to the reading, and for each degree below, .3 is subtracted. i 

115. Reading the lactometer. For determining the 
specific gravity of milk in factories or private dairies, tin 
or copper cylinders are recommended, l^/o inches in 
diameter and 10 inches high, with a base about four 
inches in diameter (see fig. 39) ; another form of speci- 
fic-gravity cylinders, in use in chemical laboratories, is 
shown in fig. 40. The cylinder is filled with milk of a 
temperature ranging between 50° and 70° F., to within 

^A special form of lactometer that will allow of very accurate read- 
ings has been constructed by Poetschke (see Jr. Ind. and Eng. Chem., 
1911, p. 405). 



The Lactometer and Its Application. 107 

an inch of the top, and the lactometer is slowly lowered 
therein until it floats; it is left in the milk for about 
half a minute before lactometer and thermometer read- 
ings are taken, both to allow the escape of air which 
has been mixed with the milk in pouring it, prepara- 
tory to the specific-gravity determination, and to allow 
the thermometer to adjust itself to the tem- 
perature of the milk. The lactometer should 
not be left in the milk more than a minute 
before the reading is taken, as cream will soon 
begin to rise on the milk, and the reading, 
if taken later, will be too high, as the bulb 
of the lactometer will then be floating in par- 
tially skimmed milk (24). In reading the lac- 
tometer degree, the mark on the scale plainly 
visible through the upper portion of the 
meniscus of the milk should be noted. Ow- 
inff to surface tension the milk in immediate 

"^ , . Fu:. 41). ^;po- 

contact with the lactometer stem will rise cific-gravity 

cylinder. 

above the level of the surface in the cylinder, 
and this must be taken into consideration in making the 
readings. It is not necessary to read closer than one- 
half of a lactometer degree in factory or dairy work. 

ii6. Time of taking lactometer readings. The spe- 
cific gravity of milk should not be determined until an 
hour or two after the milk has been drawn from the 
udder, as too low results are otherwise obtained {Reck- 
nageVs phenomenon).^ The cause of this phenomenon 
is not definitely understood; it may come from the es- 
cape of gases in the milk, or from changes occurring in 

1 Milchztff. 1883. 410 ; bull. 48. Chem. Div.. U. S. Dept. of Agriculture, 
p. 191 ; Analyst, 1894, p. 76. See also Fleischmann and Wiegner, Jr. 
f. Ldw., 1913, pp. 283-323. * 



108 Testing Milk and Its Products. 

the mechanical condition of the nitrogenous compo- 
nents of the milk. The results obtained after a couple 
of hours will, as a rule, come about one degree higher 
than when the milk is cooled down directly after milk- 
ing and its specific gravity then determined. 

117. Influence of solid preservatives on lactome- 
ter readings. When potassium bi-chromate, corrosive 
sublimate, etc., is added to milk samples to preserve 
them from souring (190), the specific gravity of the 
milk will be increased ; with the quantity usually added 
(V2 gi'am to a pint of milk) the increase amounts to 
about 1 lactometer degree, and this correction of lacto- 
meter readings should be made with milk samples pre- 
served in this manner. To avoid this error, Dr. Eich- 
loff^ recommends the use of a solution of potassium bi- 
chromate in water (43 grams to 1 liter), the specific 
gravity of which is 1.032, or similar to that of average 
milk; 5 cc. of this solution is required for a pint of 
milk. No correction is necessary for the dilution with 
this small amount of liquid preservative. 

118. Cleaning the lactometer. The lactometer should 
be cleaned directly after using, by rinsing with cold 
water; it is then wiped dry with a clean cloth and 
placed in the case. 

ii8a. Testing the accuracy of lactometers. The 
correctness of lactometers may be determined with a 
fair degree of accuracy by placing them in different 
salt solutions prepared by dissolving exactly 3, 4, and 5 
grams of pure dairy salt in 100 grams (cc.) of water. 
The specific gravities at 60° F. of solutions thus ob- 

^ Technik der Milchfriifung, p. 98. 



The Lactometer and Its Application. 109 

tained are 1.022, 1.029, and 1.036, for 3, 4, and 5 pei 
cent, solutions, respectively. 

Calculation of Milk Solids. 

119. A number of chemists have prepared formulas 
for the calculation of milk solids when the fat content 
and the specific gravity (lactometer reading) of the 
milk are known. By careful work with milk tester and 
lactometer it is possible by means of these formulas to 
determine the composition of samples of milk with con- 
siderable accuracy, both cutside of and in chemical lab- 
oratories. As the complete formulas given by various 
chemists (Behrend and Morgen, Clausnitzer and Mayer, 
Pleischmann, Hehner and Richmond, Richmond, Bab- 
cock)^ are very involved, and require rather lengthy 
calculations, tables facilitating the figuring have been 
prepared. The formulas in use at the present time, in 
this country and abroad, arc those proposed by Fleisch- 
tnann, Hehner and Richmond, or Babcock. Babcock's 
formula is the one generally taught in American dairy 
schools and is therefore given here ; it forms the foun- 
dation for Table VI in the Appendix for the calculation 
of solids not fat. 

By the use of these tables the percents of solids not 
fat may be found, corresponding to lactometer read- 
ings from 26 to 36, and to fat contents from to 6 
per cent. The formula, as amended in 1895,^ is as fol- 
lows, S being the specific gravity and / the per cent, of 
fat in the milk. 

solids not fat=(^gi^|=fg-,-l)(100-f)2.5 

1 Agricultural Science, vol. Ill, p. 139. 

" Wisconsin experiment station, twelfth report, page 120. 



110 Testing Milk and Us Products. 

The derivation of this formula is explained in the re- 
port referred to. 

I20. Short formulas. The tables made up from this 
formula, giving the percentages of solids not fat corre- 
sponding to certain per cents, of fat and lactometer 
readings, are given in the Appendix. A careful exam- 
ination of the tables will disclose the fact that the per 
cent, of solids not fat increases uniformly at the rate 
of .25, or one-fourth of a per cent, for each lactometer 
degree, and .02 per cent, for each tenth of a per cent, of 
fat. This relation is expressed by the following simple 
formulas : 

Solids not f at=i4 L -f .2 f 
Total solids=i4 L + 1.2 f, 

L being the lactometer reading at 60° F. (specific gravity 
X 1000—1000), and / the per cent, of fat in the milk. 

Eule: a, To find the per cent, of solids not fat in milk, add 
two-tenths of the per cent, of fat to one-fourth of the lacto- 
meter reading, and 

b, To find the per cent, of total solids in milk, add one and 
two-tenths times the per cent, of fat to one-fourth of the lacto- 
meter reading. 

These formulas and rules are easily remembered and 
can be quickly applied without the use of tables. The 
results obtained by using them do not differ more than 
.04 per cent, from those of the complete formula for 
milks containing up to 6 per cent, of fat, and may be 
safely applied in practical work. 

The English dairy chemist Droop Richmond has 
constructed an ingenious sliding ''milk scale" which en- 
ables one to readily find the percentages of total solids 



The Lactometer and Its Application. Ill 

corresponding to different lactometer readings and fat 
contents, or the percentage of fat from total solids and 
lactometer readings.^ 

Adulteration of IMil.k. 

121. Methods of adulteration. The problem of de- 
termining whether or not a sample of milk is adulter- 
ated becomes an important one in the work of milk in- 
spectors and food chemists. ^Managers of creameries 
and cheese factories are also sometimes interested in 
ascertaining possible adulterations in the case of some 
patron's milk, although since the general introduction of 
the Babcock test in factories and the payment for the 
milk on the basis of the amount of butter fat delivered, 
the temptation to water or skim tlie milk has been 
largely removed. In thv3 city milk trade, especially in 
our larger cities, watered or skimmed milk is occasion- 
ally met with, in spite of the vigilance of their milk in- 
spectors or the officers of the city boards of health. 

When the origin of a suspected sample of milk is 
known, a second sample should always be taken on the 
premises, if possible, by or in the preseaice of the in- 
spector, and the composition of the two samples com- 
pared. If the suspected sample is considerably lower 
in fat content than the second, so-called control-sample, 
and has a normal per cent, of solids not fat, it is 
skimmed ; if the solids not fat are below normal, it is 
watered; and if both these percentages are abnormally 
low, the sample is most likely both watered and 
skimmed (126). 

^ Dairy Chemistry, p. 61. 



112 Testing Milk and Its Products. 

122. Latitude of variation. In order to determine 
whether or not a sample of milk is skimmed or watered, 
or both skimmed and watered, the per cents, of fat and 
of solids not fat in the sample must be ascertained, and 
if a control-sample can be secured, these determina- 
tions for both samples compared. The proper latitude 
to be allowed for the natural variation in the composi- 
tion of milk differs according to the origin of the milk ; 
in case of milk from single cows, the variations in fat 
content from day to day may exceed one per cent., al- 
though under ordinary conditions the per cent, of fat 
in most cow's milk will not vary that much. The con- 
tent of solids not fat is more constant, and rarely va- 
ries one-half of one per cent, from day to day with 
single cows. Cows in heat or sick cows may give milk dif- 
fering considerably in composition from normal milk.^ 

123. Mixed herd milk is of comparatively uniform 
composition on consecutive days, and as most milk of- 
fered for sale or delivered to factories is of this kind, 
the task of the milk inspector is made considerably 
easier and more certain on this account. Daily varia- 
tions in herd milk beyond one per cent, of fat and one- 
half per cent, of solids not fat, are suspicious and may 
be taken as fairly conclusive evidence of adulteration. 
This is especially true in case the control-sample shows a 
comparatively low content of fat or solids not fat (159). 

124. Legal standards. Wliere a control-sample can- 
not be taken, the legal standards of the various states 
for fat or solids in milk are used as a basis for calculat- 



1 Blythe, Foods, their Composition and Analysis, London, 1903, p. 
250 et seq. 



The Lactometer and Its Application. 113 

ing the extent of adulteration of a sample of milk. A 
list of legal standards for milk in this country and 
abroad is given in the Appendix. These standards de- 
termine the limits below which the milk offered for sale 
within the respective states must not fall. Legally it 
matters not whether a sample of milk offered for sale 
has been skimmed or watered by the dealer or by the 
cow ; in the latter case, the cows producing the milk are 
of a breed or a strain that has been bred persistently 
for quantity of milk, without regard to its quality. In 
most states the legal standard for the fat content of 
milk is 3 per cent., and for solids not fat 9 per cent. 
There are, however, cows which at times produce milk 
containing only 2.5 to 2.8 per cent, of fat, and less than 
8.5 per cent, solids not fat. Such milk cannot therefore 
be legally sold in most states in the Union, and the 
farmer offering such milk for sale, even if he does not 
know the composition of the milk produced by his cows 
is liable to prosecution just as if he had directly watered 
the milk. By mixing the milk of several cows, the 
chances are that the mixed milk will contain more fat 
and solids not fat than called for by the legal standard; 
if such should not be the case, cows producing richer 
milk must be added to the herd so as to raise the qual- 
ity of the herd milk up to the legal standard, or the 
cows giving very thin milk must be disposed of. 

125. The specific gravity of the milk solids. A calcula- 
tion of the specific gravity of the milk solids is of considerable 
assistance in interpreting the results of analyses of suspected 
milk samples. The milk solids vary but slightly in specific 
gravity, viz., between 1.25 and 1.34, the richer milks having sol- 

8 



114 Testing Milk and Its Products. 

ids of low specific gravities. The specific gravity of the milk 
solids is calculated by means of Fleischmann 's formula 

t 



s=- 



100 s -100 
t- 



s 

S being the sp. gr. of the milk solids, s that of the milk and t 
the total solids of the milk. 

Example: A sample of milk has been found to contain 13.0 

per cent, of solids, sn. gr. 1.032; then lOOXi. 032-100 __3-^qj^ 

13.0-3;101=9.899; -g^.f^V =1-31, the specific gravity of the milk 
solids. 

The specific gravity of the solids does not change if the milk 
is watered, while it is increased when the milk is skimmed. If a 
sample of milk of the composition given in the preceding ex- 
ample had been watered so as to reduce the solids to 11.7 per 
cent, and the specific gravity to 1.0291 (as would be the case 
when 10 per cent, of water was added), we would again have, 
by calculation as above, S=1.31. If, on the other hand, the 
milk was skimmed so as to reduce the solids to 11.7 per cent., 
thereby increasing the specific gravity of the milk to, say 1.035, 
we would have by substituting these values in the preceding 
formula, S^1.41, showing conclusively that the milk had been 
skimmed. 

An addition of skim milk to whole milk would have the same 
effect as skimming, as regards the composition of the latter, and 
the specific gravity of its solids. 

The specific gravity of pure butter fat at 60° F. is .93, and 
of the fat-free milk solids, 1.5847 (Fleischmann). The solids of 
skim milk have a specific gravity of 1.56. Samples of whole 
milk, the solids of which have a specific gravity above 1.34 are 
suspicious, and a specific gravity over 1.40 is conclusive evidence 
of skimming. 

To facilitate the calculation of the specific gravity of milk 
solids. Table IV is given in the Appendix, showing at a glance 
the value of ^'^Qs-ioo ^^^ specific gravities between 1.019 and 
1.0369. An example will readily illustrate the use of the table. 

Example: A sample of milk has a specific gravity of 1.0343 
and contains 12.25 per cent, solids. In Table IV, we find in the 



The Lactometer and Its Application. 115 

norizontal line beginning with 1.034 under the column bended 

0.0003, the figure 3.316, which is the value for ^*^^^~^^^ when 
s=1.0343. Introducing this value and that of the total solids 
in the formula, the calculation is 12.25—3.316=8.934; 12.254- 
8.934:=1.37, which is the specific gravity of the solids in this 
ease. 

126. To recapitulate. Adulteration of milk by water- 
ing or skimming, or both, may be established by a com- 
parison of the composition of the suspected sample with 
that of a control-sample, or if none such can be ob- 
tained, with the legal standards. If the composition of 
the two samples varies appreciably, the milk has been 
adulterated, and the character of the adulteration is 
shown from the following statement: 

// the analysis of the suspected sample 
shows the milk is 



sp. gr. of milk 1 j^^^. j 

fat and solids not fat J > watered 

sp. gr. of solids normal ) 

sp. gr. of milk and of solids ^, . , ] 

solids not fnt | "ig'^ I skimmed 

fat and solids _— low ) 

sp. gr. of milk normal "j watered 

sp. gr. of solids normal or high y and 

fat and solids not fat low j skimmed 

The extent of the adulteration is determined as given 
below. 

127. Calculation of extent of adulteration.^ In the 

following formulas, percentages found in the control- 
samples, if such are at hand, are always substituted for 
the legal standards. 

a. Skimming.— 1. If a sample of milk has been 
skimmed, the following formula will give the number 
of pounds of fat abstracted from 100 lbs. of milk : 

1 Woll, Handbook for Farmers and Dairymen, New York, 1907, pp. 

267-8. 



116 Testing Milk and Its Products. 

Fat abstracted=legal standard for fat — f, . . (I) 
f being the per cent, of fat in the suspected sample. 

2. The following formula will give the per cent, of 
fat abstracted, calculated on the total quantity of fat 
originally found in the milk : 

-^0°- ... .a^rL K . ----- - (") 

b. Watering.— li a sample is watered, the calcula- 
tion is most conveniently based on the percentage of 
solids not fat in the milk. The percentage adulteration 
may be expressed either on basis of the amount of 
water present in the adulterated milk, or the amount of 
water added to the original milk: 

1. Percent, of foreign (extraneous) water in the adul- 
terated milk=100—. T— . = — ^^ TT^, r:F^(ni) 

legal standard tor solids not lat 

S being the per cent, of solids not fat in the suspected 
sample. 

Example: A sample of milk contains 7.5 per cent, solids not 
fat; if the legal standard for solids not fat is 9 per cent., then 
100 — 7.5x1 :^ig^7^ shows the per cent, of extraneous water 
in the milk. 

2. Watering of milk may also be expressed in per 
cent, of water added to the original milk, by formula IV : 

Per cent, of water added to the original milk 

lOOX leg. stand, for sol. not fat 
= -100 (IV) 

In the example given above,--- — 100=20 per cent 
of water was added to the original milk. 

c. Watering and skimming. — If a sample has been 
both watered and skimmed, the extent of watering is 



Babcock Test for other Milk Products. 117 

ascertained by means of formula (III) or (IV), ana 

the fat abstracted found according to the following 

formula : 

Per cent, fat abstracted= 

, - » , leg. stand, for sol. not fat „ ,,^. 

leg. stand, for fat - —^ ^^ Xf . . (V) 

Example: A sample of milk contains 2.4 jjer cent, of fat and 
8.1 per cent, solids not fat; then 

Extraneous water in milk=100— '^■^^^^-=10 per cent. 
Fat abstracted=3— •''''-* =33 per cent. 

100 lbs. of the milk contained 10 lbs. of extraneous water and 
.33 lb. of fat had been skimmed from it. 

For methods of detection of other adulterations and 
of preservatives in dairy products, see Chap. X, 299, 
et seq. 



Questions. 

1. What is the weight of 1000 cc. of (a) water; (b) skim 
milk; (c) whole milk; (d) cream testing 30% fat; (e) whey; 
(f) butter fat? 

2. If the sp. gr. of a sample of milk is 1.0325 at 68° F., 
what is the lactometer reading at 60° T 

3. What effect on the sp. gr. has 1.0% solids not fat and 
1.0% fat? 

4. How can the accuracy of a lactometer be determined? 

5. If a sample of milk has a sp. gr. of 1.032 and 1:5.0% sol- 
ids, what is the sp. gr. of the milk solids? 

6. How can (a) skimmed milk, (b) watered milk, (c) 
skimmed and watered milk be detected? 

7. Give lactometer readings and percentages of fat in sam- 
ples showing (a) watering, (b) skimming, (c) watering and 
skimming. 

8. If one quart of water is added to one quart of milk, what 
per cent, of water is added, and what per cent, extraneous water 
does the mixture contain? 



118 Testing Milk and Its Products. 

9. How many pounds of fat have been removed from 100 
pounds of a sample of milk testing 2.6%, and what per cent, of 
the fat was removed? 

10. If a sample of milk contains 7.0% solids not fat, what 
per cent, water was added and how much extraneous water did 
the sample contain? 

11. What has probably been done to each of the following 
samples of milk, that were found to contain (a) 7.2 per cent, 
solids not fat, 2.6 per cent, fat; (b) 9.0 per cent, solids not fat, 
2.5 per cent, fat; (c) 6.5 per cent, solids not fat, 2.4% fat? 

12. What is the per cent, solids not fat and what is the con 
dition of each of the following samples of milk: 

Lactometer Beading. per Cent Fat. 

4.0 
2.5 
3.5 
2.5 
2.4 



(a) 


32.0 at 58° 


F. 


(b) 


33.5 at 56° 


F. 


(e) 


30.0 at 63° 


F. 


(d) 


28.0 at 54° 


F. 


(e) 


27.4 at 69° 


F. 



CHAPTER VII. 
TESTING THE ACIDITY OF MILK AND CREAM, 

128. Cause of acidity in milk. Even directly after 
milk is drawn from the udder it will be found to have 
an acid reaction, when phenolphtalein is used as an in- 
dicator.^ The acidity of fresh milk is not due to the 
presence of free organic acids in the milk, like lactic 
or citric acid, but to acid phosphates, and possibly also 
in part to free carbonic acid gas in the milk or to the 
acid reaction of casein. Even in case of so-called sweet 
milk, nearly fresh from the cow, a certain amount of 
acidity, viz., on the average about .07 per cent., is there- 
fore found. When the milk is received at the factory 
it will rarely test less than .10 per cent, of acid, calcu- 
lated as lactid acid; some patrons bring milk day after 
day that does not test over .15 per cent, of acid; that 
of others tests from .20 to .25 per cent., and some lots, 
although very rarely, will test as high as .3 of one per 
cent, of acid. It has been found that milk will not 
usually smell or taste sour or ''turned," until it con- 
tains .30 to .35 per cent, of acid. 

129. The acidity in excess of that found normally in 
milk as drawn from the udder, is due to other causes 
than those described. Bacteriological examinations of 
milk from different sources and of milk of the same 
origin at different times have shown that there is, roughly 
speaking, a direct relation between the bacteria found 

* Freshly drawn milk shows an amphoteric reaction to litmus, 1. e., 
It colors blue litmus paper red, and red litmus paper faintly blue. 



120 Testing Milk and Its Products. 

in normal milk, and its acidity; the larger the number 
of bacteria per unit of milk, the higher is, in general, 
the acidity of the milk. The increase in the acidity 
of milk on standing is caused by the breaking 
down of milk sugar into lactic acid through the activi- 
ties of acid-forming bacteria. Since the bacteria get 
into the milk through a lack of cleanliness during the 
milking, or careless handling of the milk after the 
milking, or both, it follows that an acidity test of new 
milk will give a good clue to the care bestowed in hand- 
ling the milk. Such tests will show which patrons take 
good care of their milk and which do not wash their 
cans clean, or their hands and the udders of the cows 
before milking, and have, in general, dirty ways in milk- 
ing and caring for the milk. The acidity test is always 
higher in summer than in winter, and is generally high 
in the case of milk kept for more than a day (Monday 
milk), or delivered after a warm, sultry day or night. 
The bacteria have had a good chance to multiply greatly 
in such milk, even if it be kept cooled down to 
40°-50° F., and as a result considerable quantities of 
lactic acid have been formed. The determination of the 
acidity of fresh milk is explained in detail below (147). 
130. Method of testing acidity. Methods of meas- 
uring the acidity or alkalinity of liquids by means of 
certain chemicals giving characteristic color reactions in 
the presence of acid or alkaline solutions (so-called 
volumetric methods of analysis) have been in use for 
many years in chemical laboratories. They were applied 
to milk as early as 1872 by Soxhlet,^ and the method 

1 Jour. f. prakt. Chemie, 1872, p. 6, 19. 



Testing the Acidity of Milk and Cream. 121 

worked out by Soxhlet and Henkel has since been in 
general use by European chemists. They measured out 
50 cc. of milk to which was added 2 cc. of a 2 per cent, 
alcoholic solution of phenolphtalein, and this was ti- 
trated with a one-fourth normal soda solution^ (see 
below). In this country, Dr. A. G. Manns in 1890 pub- 
lished the results of work done in th-e line of testing 
the acidity of milk and cream,^ and the method of pro- 
cedure and apparatus proposed by him has become 
known under the name of Manns' test, and is being 
advertised as such by dealers in dairy supplies. 

131. Manns' test. The acid in milk or cream is 
measured by using an alkali solution of a certain strength^ 
with an indicator which shows by a change of color in 
the milk when all its acid has been neutralized. Any of 
the alkalies, soda, potash, ammonia, or lime can be used 
for making the standard solution, but it requires the 
skill and apparatus of a chemist to prepare it of the 
proper strength. A tenth-normal solution^ of caustic 
soda is the alkali solution used most frequently in de- 

1 Fleisohmann. Lehrb. d. Milchwirtschaft, 3rd ed., p. 57. 

* Illinois experimont station, bulletin 9. 

» Normal solutions, as a general rule, are prepared so that one liter 
shall contain the hydrogen equivalent of the active reagent weighed 
in grams (Sutton). Caustic soda (NaOii; is made up of an atom each 
of sodium (Na), oxygen (O), and hydrogen (H) ; its molecular weight 
is therefore 

23+16+1=40 
NaOH 

A normal soda solution then is made by dissolving 40 grams of soda 
in water, making up the volume to 1000 cs.:& one-tenth normal solu- 
tion will contain one-tenth of this amount of soda, or 4 gra-ns dissolved 
in one liter. One cubic centimeter of the latter solution will contain 
.004 gram of soda, and will neutralize .009 gram of lactic acid. The 
formula for lactic acid is CaH^O, (see p, 16), and its molecular weight 
is therefore 3x12+6x1+3x16=90. A tenth-normal solution of lactic 
acid contains 9 grams per liter, and .009 gram per cubic centimeter. 



122 



Testing Milk and Its Products. 



termining the acidity of milk, and is the solution labeled 
Neutralizer of the Manns' test. 

The indicator used is a solution of phenolphtalein, a 
light yellowish powder; its compounds with alkalies are 
red, in weak alkaline solutions pink colored, while its 
acid compounds are colorless. The phenolphtalein solu- 
tion used is prepared by dissolving 10 grams in 300 cc. 
of 90 per cent, alcohol (Mohr). 

132. In testing the acidity of either 
milk or cream it is necessary to meas- 
ure out with exactness the quantity of 
liquid to be tested; Manns recom- 
mended using a 50 cc. pipette. This 
amount of milk or cream is measured 
into a clean tin, porcelain or glass cup, 
a few drops of the phenolphtalein so- 
lution are added, and the Neutral- 
izer (or alkali solution) is cautiously 
dropped in from a burette, the point at 
which the solution stands before any is 
drawn off being noted. By constant 
stirring during this operation it will be 
noticed that the pink color formed by 
the addition of even a drop of alkali 
solution will at first entii^ely disappear, 
but as more and more of the acid in 
the sample becomes neutralized, 
the color will disappear more 
slowly, until finally a point is 
reached when the pink color re- 

FiG. 41. Apparatus used . p • -kt 

in Manns' test. maius permanent tor a time. JNo 




Testing the Acidity of Milk and Cream. 123 

more alkali should be added after the first appearance 
of a uniform pink color in the sample. This color will 
fade and gradually disappear again on standing, owing 
to the effect of the carbonic acid of the air, to which 
phenolphtalein is very sensitive. The amount of the 
alkali solution used for the test is then obtained from 
the reading on the scale of the burette. The per cent, 
of acid in the sample is calculated by multiplying the 
number of cc. of alkali solution used, by .009 and di- 
viding the product by the number of cc. of the sample 
tested, the quotient being multiplied by 100. 

c. c. alkali X. 009 ^,,^^ 

Per cent. aeidity= : — — — -,X100 

c. c. sample tested 

If 50 cc. of cream required 32 cc. of alkali solution to 
produce a permanent pink color, the per cent, of acid in 

the cream would be '^ ^ Xl00=.58 per cent. A 

part of this calculation may be saved by using a factor 
for multiplying the number of cc. of alkali added in 
each test. This factor is obtained by dividing .009 (the 
number of grams of lactic acid neutralized by one cc. 
of alkali solution) by the number of cc. of sample 
tested, and multiplying the quotient by 100. If a 50 
cc. pipette is used for measuring the sample to be tested, 
the factor will be (.009^50) Xl00=.018; if a 25 cc. 
pipette is used, the factor will be (.009^25) X 100= 
.036: and if a 20 cc. pipette is used, (.009^20) X 100= 
.045 will be the factor to be applied in calculating the 
per cent, of acidity, the number of cc. of alkali used 
being in all cases multiplied by the particular factor 
corresponding to the volume of the sample tested. 



124 Testing Milk and lis Products. 

133' If a Babcock milk test pipette is used for meas- 
uring the milk or cream to be tested for acidity, the 
factor will be (.009^-17.6) XlOO= 051. This is so nearly 
.05 that sufficiently accurate results may be obtained by 
simply dividing the number of cc. used by two ; the re- 
sult will be the tenths of per cent, of acid in the sample 
tested, e. g., if 17.6 cc. of cream required 12 cc. of one- 
tenth normal alkali to give a pink color, then the per 
cent, of acid is 12-h2=.6 per cent. If one-fifth normal 
alkali is used for testing, the per cent, of acidity is 
shown directly by the number of cc. used (Vivian).* 

134. Manns' testing outfit The apparatus (see fig. 41) 
and chemicals necessary for testing the acidity of milk or cream 
by the so-called Manns' test include one gallon of a one-tenth 
normal alkali solution; four ounces of an alcoholic solution of 
phenolphtalein, a 50 cc. glass burette provided with a pinch- 
cock, a burette stand and a pipette for measuring the sample. 
This outfit will make about 100 tests and is sold for $5.00.' 

135- The alkaline tablet test. Solid alkaline tab- 
lets were proposed by Farrington in 1894, as a substi- 
tute for the liquid used in Manns' test.^ It was found 
possible to mix a solid alkali carbonate and coloring 
matter, and compress the mixture into a small tablet, 
which would contain an exact amount of alkali. The 
advantage of the tablets lies in the fact that they 

^ Van Norman recommends the use of a 50th normal solution for 
testing cream (see Purdue exp. sta., bull 104). 37 cc. oi a normal soda 
solution is diluted to 1850 cc. in a two-quart bottle, such as is used for 
mineral waters. Each cc. of this solution represents .01 cc. of acidity 
when 17.6 cc. of cream is measured off. The titration is made in the 
usual manner, using phenolphtalein as an indicator. See also Cornell 
Univ. circ. No. 7. 

'^ Devarda's acidimeter (Milchzeitung 1896, p. 785) is based on the 
same principle as Manns' test; one-tenth soda solution is added to 100 
cc. of milk in a glass-stoppered granulated flask, z cc. of a 4 per cent, 
phenolphtalein solution being used as an indicator. The graduations 
on the neck of the flask give the "degrees acidity" directly. 

^ Illinois experiment station, bulletin 32, April, 1894. 



Testing the Acidity of Milk and Cream. 125 



will keep far better than a standard alkali solution, 
and they can be safely sent by mail; they also require 
less apparatus and are considerably cheaper than 
standard alkali solutions ; 1000 of these tablets, costing 
$2.00, will make about 400 tests.^ Similar alkaline 
tablets were placed on the market in Europe at about 
the same time, viz., Stokes' Acidity Pellets in 189-3, 
and Eiehler's Sdurepillen (acid pills) in 1895.^ 

Two methods of using the tablets have been proposed, 
one, for the titration (determination of acidity) of rip- 
ening cream in the manufacture of sour-cream butter; 
and the other, for determining the approximate acidity 

of different lots of apparently 
sweet milk or cream. 

136. Determination of acidity 
in sour cream. The method is 
equally applicable for the deter- 
mination of the acidity of sour 



lOt^ 



LiO 



170 



.^D)l 




12> 



Qiip 



Q)y I indi 



lew'in^clep iG)j under' 

Fig. 42. Appaniius used for determining the acidity of cream or milk. 

cream, sour milk and buttermilk, but is most frequently 
employed in testing the acidity of cream, to examine 



1 The tablets are sold by dealers in dairy supplies. 

2 Milchzeitung, 1895, pp. 518-16. 



126 Testing Milk and Its Products. 

whether or not the ripening process has reached the 
proper stage for churning the cream. The apparatus 
used (see fig. 42) is as follows: 

1 17.6 cc. pipette. 

1 white cup. 

100 cc. graduated cylinders ; it is well to provide two 
or three of these, although only one is strictly necessary. 

137. Preparation of the solution. The tablet solu- 
tion formerly used was prepared by dissolving five tab- 
lets in 50 cc. of water; with 20 cc. of cream each cubic 
centimeter of this solution represents .017 per cent, of 
acid (lactic acid) in the sample tested. The amount of 
acid in a given sample is then obtained by multiplying 
the number of cubic centimeters of the tablet solution 
used, by .017. 

138. According to a suggestion made by Mr. C. L. 
Fitch,^ the strength of the solution was changed in such 
a manner that the percentages of acidity are indicated 
directly by the number of cubic centimeters of tablet 
solution used in each test. 

The 17.6 cc. pipette may be used for measuring the 
sample for acidity testing, and the results read directly 
from the graduated cylinder, if the tablet solution is 
prepared by taking one tablet for every 19.5- cc. of 
water; five tablets are therefore dissolved in 97 cc. of- 
water. 

139. As cream during its ripening process under the 
conditions present in this country generally has from 
.5 to .6 per cent, of acid before it is ready to be churned, 

1 Hoard's Dairyman, Sept. 3, 1897. 



Testing the Acidity of Milk and Cream. 127 

a 50 cc. cylinderful of tablet solution of this strength 
will not be sufficient to make a test of cream containing 
over .5 per cent, of acid, although it is enough for test- 
ing the cream up to this point during the ripening pro- 
cess. The acid-testing outfit should therefore contain a 
100 cc. graduated cylinder, instead of one of 50 cc. capa- 
city, so that cream of any amount of acidity up to 1 
per cent, can be tested. A tablet solution of the strength 
given has not only the advantage over the solution pre- 
viously recommended (5 tablets to 50 cc. of water) ^ 
of showing the p(r cent, of acidity directly, without 
tables or calculations, but being weaker, the unavoid- 
able errors of determination are decreased by its use. 

Since a 17.6 cc. pipette is found in creameries and 
dairies with the Babcock test outfit, no new apparatus is 
necessary for making the acidity test in the manner 
given. 

140. The preparation of the standard solution is as 
follows: Five tablets are placed in the 100 cc. cylinder 
which is filled to the 97 cc. mark with clean soft water.^ 
The cylinder is tightly corked, shaken and laid on its 
side, as the tablets dissolve more quickly when the cyl- 
inder is placed in this position than when left upright 
with the tablets at the bottom. Several cylinders con- 
taining the tablet solution may be prepared at a time; 
as soon as one is emptied, tablets and water are again 
added, and the cylinder is corked and placed in a hori- 

^ Illinois experiment station, bulletin 32 ; Wisconsin experiment sta- 
tion, bulletin 52. 

' Condensed steam or rain water should be used, and not hard or 
alkali water, since the impurities in these affect the strength of the 
tablet solution. 



128 Testing Milk and Its Products. 

zontal position. In this way fresh solutions ready for 
testing are always at hand. The cylinder is kept tightly 
corked while the tablets are dissolving, so that none of 
the liquid is lost by the shaking. It is well to pnt the 
tablets in the cylinder with water at night; the solution 
will then be ready for use in the morning. Excepting 
a flocculent residue of inert matter, * 'settlings," which 
will not dissolve, the tablets must all disappear in the 
solution before this is used. The strength of the tablet 
solution does not change perceptibly by standing, at 
least for one week. The only precaution necessary is 
to avoid evaporation of the solution by keeping the cyl- 
inders tightly corked. The solid tablets will not change 
if kept dry, any more than dry salt changes by age. 

141. Accuracy of the tablets. The tablets have been 
repeatedly tested by chemists and found to be accurate 
and uniform in composition. Tests made with the 
tablets according to the directions here given can there- 
fore be relied on as correct. The alkali solution is very 
sensitive, however, and should not be measured in a cyl- 
inder which has been previously used for measuring 
sulfuric acid, as the smallest drop or film of acid from 
a dish or from the operator's fingers will change the 
strength of the standard tablet solution. 

141a. Powdered sodium carbonate weighed out in 
the exact quantity required for making a gallon of 
tenth normal solution has of late been placed on the 
market; these ''test powders" are cheaper than alka- 
line tablets and when put out by a reliable firm are 
equally as accurate as these. 



Testing the Acidity of Milk and Cream. 129 

142. Making the test. The cream to be tested is 
thoroughly mixed, and 17.6 cc. are measured into the 
cup. The pipette is rinsed once with water, and the 
rinsings added to the cream in the cup. A few cc. of 
the tablet solution prepared as given above are now 
poured from the cylinder into the cream and mixed 
thoroughly with it by giving the cup a gentle rotary 
motion. The tablet solution is added in small quanti- 
ties until a permanent pink color appears in the sam- 
ple. The number of cc. of tablet solution which has 
been used to color the cream is now read off on the 
scale of the cylinder. 

In comparing the results of one test with another, 
the same shade of color should always be adopted.^ 
The most delicate point is the first change from pure 
white or cream color to a uniform pink which the sam- 
ple shows when the acid contained therein has beer 
neutralized. This shade of color is easily recognized 
with a little practice. The pink color is not permanent 
unless a large excess of the alkaline solution has been 
added, on account of the influence of the carbonic acid 
of the air (132), and the operator should not therefore 
be led to believe by the reappearance of the white color 
after a time, that the point of neutralization was not 
already reached when the first uniform shade of pink 
was observed. 

143. Acidity of cream. 17.6 cc. of sweet cream is 

^ A helpful suggestion has been made by the Danish State Dairy In- 
structor, Dr. G. Ellbrecht, for obtaining a uniform color in acidity tests. 
Small strips of pink paper are moistened and attached to the cup or 
glass in which the titration is made, and alkali solution is added, 
until the color of the milk or cream corresponds to that of the strips. 

9 



130 Testing Milk and Its Products. 

generally neutralized by 15 to 20 cc. of this tablet solu- 
tion, representing from .15 to .20 per cent, of acid. A 
mildly sour cream is colored by 35 ec. tablet solution, and 
a sour cream ready for churning by about 50 to 60 cc. 
tablet solution. As the cream ripens, its acidity in- 
creases. The rate of ripening depends largely on the tein 
perature at which the cream is kept. Cream containing 
.5 to .6 per cent, of acid will make such butter as the 
general American market demands at the present time 
Cream showing an acid test of .55 per cent, may not be 
too sour,, but .65 per cent, of acid is very near, if not 
on the danger line, since such cream is likely to make 
strong flavored, almost rancid butter. Each lot of cream 
should be tested as soon as it is ready for ripening, and 
the result of the test will show whether the cream should 
be warmed or cooled in order to have it ready for churn- 
ing at the time desired. Later tests wdll show the rate 
at which the ripening is progressing, and the time when 
the cream has reached the proper acidity for churning. 
144. The influence of the richness of cream on the 
acid test has been studied by Professor Spillman,^ and 
others.^ Since the acidity develops in the cream serum, 
it follows that an acidity of, say .5 per cent, in a 40 
per cent, cream represents a larger acidity than in 20 
per cent, of cream, e. g. ; in the former case we have .5 
gram of acid in 60 grams of serum (=.83 per cent, of 
the serum) ; in the latter case .5 gram acid is found in 
80 grams serum (=.63 per cent, of the serum). There- 

^ Washington experiment station, bulletin 32. 

2 Chicago Dairy Produce, April 21, 1900, p. 30 ; Iowa expt. sta., bull. 
52. 



■^=^ 



Testing the Acidity of Milk and Cream. 131 

fore, rich cream need not be ripened to as high a degree 
of acidity as thin cream. A table is given in the Iowa 
bulletin referred 'to, showing the relation between the 
richness and the acidity of cream. 

145. Spillman's cylinder. The graduated cylinder shown in 
fig. 4.3 was devised by Professor Spillman for use in testing the 
acidity of milk and cream with Farrington 's alkaline tablets. 
The following directions are given for making 
tests with this piece of apparatus:^ 

"All that is needed in addition to the acid-test 
graduate shown in the accompanying illustration, 
is a common prescription bottle of six or eight 
ounce capacity, anrl a package of Farrington 's 
alkaline tablets. Fill the bottle with water and 
add one tablet for each ounce of water in the 
bottle. Shake the bottle frequently to aid in dis 
solving the tablets. 

'^Making the test. In making the test, the 
acid-test graduate is filled to the zero mark with 
the milk or cream to be tested. The tablet solu- 
tion is then added, a little at a time, and the 
graduate shaken after each addition, in order to 
thoroughly mix the milk and the tablet solution. 
In shaking the graduate, give it a rotary motion pj^^ ^^ Snili- 

to prevent spilling any of the liquid. Continue man's cylinder, 
IT i.1. i. I 1 i 1 i.' i.-i i. • 1 used in delor- 

adding the tablet solution until a permanent pink mining tho acid- 
color can be detected in the milk. The level of i^y of cream or 
the liquid in the graduate, measured by the scale 
on the graduate, will then show the per cent, of the acidity of the 
milk. It is best to stand the graduate on a piece of white paper, 
so that the first pink coloration of the milk may be easily de- 
tected. ' ' 

146. The Marschall acid test (see fig. 44) is a con- 
venient apparatus for determining the acidity of milk, 
cream, or whey.- It is used with a tenth-normal alkaline 






^ Washington experiment station, bulletin 24. 
^ See Wis. exp. sta.. bull. 129. 



132 



Testing Milk and Its Products. 



solution C'Neutralizer"), 9 cc. of milk, cream, etc., 
being measured out for the test, and alkali solution 
added from the combined burette and bottle, the former 
being graduated to two-tenths of one cc. The burette 
is filled by tipping the bottle and the surplus of the 
''neutralizer" will flow back, leaving the solution at 

the zero mark. With 
the quantity of milk 
given, the readings ob- 
tained represent per 
cent of acidity direct. 

\\ 111 III I ^47* RapJtl estima- 

\\ III I ! r, tion of the acidity 

of apparently sweet 
milk or cream. a, 
Milk. The alkaline 
tablet method offers a 
ready means of esti- 
mating the acidity of 
milk or cream that is 
still sweet to the taste. 
The selection of the 
best kinds of milk 
is especially important 
in pasteurizing milk 
As previously noted, milk which gives the 
highest acid test contains, as a rule, a larger number of 
bacteria and spores not destroyed by pasteurization 
than does milk giving a low acid test (129) ; the acidity 
test may therefore be used to advantage for the pur- 
pose of selecting milk best adapted for pasteurization, 




INUICATOC 



Fig. 44. The Marschall acid test. 



or cream. 



Testing the Purity of Milk. 



133 



as well as such as is to be retailed or used in the manu- 
facture of high-grade butter and cheese. 

In distinguishing milk fit for pasteurization purposes 
from that which is doubtful, an arbitrary standard of 
two-tentlis of one per cent, of acid may be taken as the 






ft Oixrjce Bottle. "Measure 



Fig. 45. Apparatus used for rapid estimation of the aciditj' of ap- 
parently sweet milk or cream. 

upper limit for milk of the former kind. The appara- 
tus used in making this test is shown in the accompany- 
ing illustration (fig. 45), and consists of a white tea- 
cup; a four-, six-, or eight-ounce bottle, and a No. 10 
brass cartridge shell, or a similar measure. A solution 
of the tablets in water is first prepared, one tablet being 
always added to each ounce of water: four tablets in a 
four-ounce bottle; six, in a six-ounce bottle, etc., the 
amount of tablet solution prepared depending on the 



134 Testing Milk and Its Products. 

number of tests to be made at a time. The bottle is filled 
up to its neck with clean, soft water, and the solution 
prepared in the manner previously given (140). 

148. Operating the test. As each lot of milk is 
brought to the creamery in the morning and poured into 
the weigh can, a cartridge-shell dipper is filled with 
milk and this is poured into the white cup. The same or 
another No. 10 shell is now filled twice with the tab- 
let solution and emptied into the milk in the cup. In- 
stead of dipping twice with one measure or a No. 10 
shell, a tin measure can be made holding as much as two 
No. 10 shells, or the tablet solution may be made of 
double strength; that is, two tablets to each ounce of 
water and the same sized measure used for both the milk 
and the tablet solution. The liquids are then mixed in 
the cup by giving this a quick, rotary motion, and the 
color of the mixture noticed. If the milk remains white 
it contains more than two-tenths of one per cent, of acid 
and should not be used for pasteurization. If it is col- 
ored after having been thoroughly mixed with two 
measures of tablet solution, it contains less than this 
amount of acid and may, as far as acidity goes, be safely 
used for pasteurization or for any other purpose which 
requires thoroughly sweet milk. The shade of color ob- 
tained will vary with different lots of milk; the sweet- 
est milk will be most highly colored, but a milk retain- 
ing even a faint pink color with two measures of tablet 
solution, or one measure of the double strength solution 
to one measure of milk, contains less than .2 per cent, 
of acid. 



Testing the Acidity of Milk and Cream. 135 

By proceeding in the manner described, the man re- 
ceiving and inspecting the milk at the weigh-can 
is able to test the acidity of the milk delivered nearly as 
quickly as he can weigh it ; and according to the results 
of the test he can send the milk to the general delivery 
vat or to the' pasteurization vat, as the weigh-can may 
be provided with two conductor spouts. 

149. Size of measure necessary. It is not necessary 
to use a No. 10 shell for a measure in working the pre- 
ceding method; one of any convenient size that can be 
filled accurately and quickl}^, will answer the purpose 
equally well, if a measure of the same size is used for 
both the sample and the tablet solution. Each measure- 
ful of tablet solution made up as directed, will in this 
case represent one-tenth per cent, of acid in the sam 
pie tested.^ 

150. b. Cream. Cream can be tested in the way al- 
ready described for testing the acidity of fresh milk, by 
adding to one measureful of cream in the cup as many 
measures of tablet solution as are necessary to change 
the color of the cream when the two liquids are thor 
oughly mixed. If one measure of tablet solution colors 
one measure of cream, this contains less than .1 per 
cent, acid; if five measures of tablet solution are re- 
quired, the cream contains about .5 per cent, acid, etc. 
By proceeding in the manner described, the operator 
can estimate the acidity to within .05 per cent, of acid, 
if half measures of tablet solution are added. The re- 



1 In European creameries and city milk depots the alcohol test is 
often applied to every can of miiii received ; milk that is sufficiently 
sour to be noticed by the taste, wni coagulate when mixed with an equal 
volume of 70% alcohol. 



136 Testing Milk and Its Products. 

suits thus obtained are sufficiently delicate for all prac- 
tical purposes. 

151. Detection of boracic acid preservatives in milk. The 

application of the alkaline tablet test for detecting the boracic acid 
in milk was first discussed in bulletin No. 52 of Wisconsin experi- 
ment station. The acidity of the milk is increased by the addi- 
tion of boracic acid, but neither the odor nor the taste of the 
milk is affected thereby. By adding to sweet milk the amount 
of boracic acid which will keep it sweet 36 hours, its acidity may 
be increased to .35 per cent., in a sample of milk which pre- 
viously tested perhaps only .15 per cent. acid. 

As before stated, unadulterated milk will usually smell or 
taste sour or ''turned," when it contains .30 to .35 per cent, acid 
(121) ; milk testing as high as this limit, which neither smells 
nor tastes sour in any way, is therefore in all probability adul- 
terated with some preparation containing boracic acid or a simi- 
lar compound. 

152. "Alkaline tabs." These are not the alkaline tablets, 
but a substitute which was put on the market by a New York 
firm. The outfit furnished consisted of four packages of paper 
discs made of heavy filter paper, each of about the size of an old- 
style copper cent; two packages of square paper; one glass of about 
10 cc. capacity, and one small glass bottle. An investigation of 
these "Tabs" soon disclosed the fact that they were entirely 
inaccurate, and that no dependence could therefore be placed on 
the results obtained by their use. 

Questions. 

1. If 20 cc. cream require 12 cc. ^^ alkali for neutralization, 
what per cent, acid in the sample! 

2. If 1 cc. >g alkali neutralize .009 gram lactic acid, what is 
the per cent, of acid in a sample of cream, which required 12 cc. 
alkali for 25 cc. of cream? 

3. What apparatus and strength of solution must be taken 
to show per cent, acidity directly from cc. alkali used with Far- 
rington's alkaline tablets? 

4. If cream testing 20% fat has an acidity of .6%, what will 
be the corresponding acidity of cream testing 40% fat? 



CHAPTER VIII. 
TESTING THE PURITY OF MILK. 

153. The Wisconsin curd test. Cheese makers are 
often troubled with so-called floating or gassy curds 
which produce cheese defective in flavor and texture. 
These faults are usually caused by some particular lot 
of milk containing impurities that cannot be detected 
by ordinary means of inspection. The Wisconsin curd 
test is used to detect the source of these defects and 
thus enable the cheese maker to exclude the milk from 
the particular farm or cow to which the trouble is 
traced. This test is similar in principle to tests that 
have long been in use in cheese-making districts in 
Europe, notably in Switzerland,^ but was worked out 
independently at the Wisconsin Dairy School in 1895 
and is now generally known as the "Wisconsin Curd 
Test. "2 

154. Method of making the test. Pint glass jars, 
thoroughly cleaned and sterilized with live steam, are 
provided; they are plainly numbered or tagged, one 
jar being provided for each lot of milk to be tested. The 
jars are filled about two-thirds full with milk from the 
various sources; it is not necessary to take an exact 

1 Herz, Unters. d. Kuhmilch, Berlin, 1889, p. 87 ; Siats, Unters. landw. 
wicht. Stofife, 1903, p. 140. 

2 Wisconsin experiment station, twelfth report, p. 148. The appar- 
atus used for the test was greatly improved in 1898, and a description 
of the improved test is given in bulletin No. 67 and the annual report 
of the Station for 1 R1>S (fifteenth report, pp. 47-.^.3), from which source 
the accompanying illustration is taken (see fig. 46). 



138 



Testing Milk mid Its Products. 



quantity; they are then placed in a water tank, the 
water of which is heated until the milk in the jars has 
a temperature of 98° F. In transferring the thermom- 
eter used from one jar to another, special care must be 
taken to clean it each time in order to prevent contami- 
nation of pure lots of milk by impure ones. 

When the milk has reached a temperature of 98°, 
add to each sample ten drops of rennet extract, and mix 
by giving the jar a rotary motion. The milk is thus 
curdled, and the curd allowed to stand for about twenty 




Fig. 46. Cross-section of tho Wisconsin curd tost, T.7-T.I", testini; 
jars showing different stages of test; WL, water line; M, milk.; F, 
frame ; WS, stand to support cover ; AI, drain holes ; WO, water out- 
let ; DP, drain pail. 

minutes until it is firm. It is then cut fine with a case 
knife, and stirred at intervals for one-half to three- 
quarters of an hour sufficiently to keep the curd from 
matting under the whey. When the cubes are quite firm 
the whey is poured off and the curd left to mat at the 
bottom of the bottles if the old form of apparatus is 
used. The best tests are made when the separation of 
the whey is most complete. By allowing the samples to 
stand for a short time, more whey can be poured off, 
and the curd thereby rendered firmer. The water around 
the jars is kept at a temperature of 98°, the vat is cov- 



Testing the Purity of Milk. 139 

ered, and the curds allowed to ferment in the sample 
jars for six to twelve hours. 

During this time the impurities in any particular 
sample will cause gases to be developed in the curds so 
that by examining these, by smelling of them and cut- 
ting them with a sharp knife, those having a bad flavor, 
or a spongy or in any way abnormal texture may be 
easily detected, and thus traced to the milk causing the 
trouble. 

Since the curd test was first described, several modi- 
fications have been made in the apparatus. In one of 
these the bottles are held in a covered metal frame so 
that all of them can be drained at once by inverting the 
frame. 

155. By proceeding in the way described with the 
milk from the different cows in a herd, the mixed milk 
of which produced abnormal curds, the source of con- 
tamination in the herd may be located. Very often the 
trouble will be found to come from the cows drinking 
foul stagnant water or from fermenting matter in the 
stable. In the former case the pond or marsh must be 
fenced off, or the cows kept away from it in other ways; 
in the latter, a thorough cleaning and disinfection of 
the premises are required. If the milk of a single cow 
is the source of contamination, it must be kept by itself, 
until it is again normal; under such conditions the milk 
from the healthy cows may, of course, safely be sent 
to the factory. 

156. The fermentation test. The Gerber fermentation 
test (see figf. 47) also furnishes a convenient method for 
examining the purity of different lots of milk. The test consists 
of a tin tank which can be heated by means of a small lamp, 



140 



Testing Milk and Its Products. 



and into which a rack fits, holding a certain number of cylin- 
drical glass tubes; these are all numbered and provided with a 
mark and a tin cover. 
In making the test, the 
tubes are filled to the 
mark with milk, the num- 
ber of each tube being 
recorded in a note book, 
opposite the name of the 
patron whose milk was 
placed therein. The 
tubes in the rack are 
put in the tank, which is 
two-thirds full of water; 




Fin. 47. Thp rjprber fprmentarinn test. 



the temperature of the water is kept at 104-106° F., for 
six hours, when the rack is taken out, the tubes gently shaken, 
and the appearance of the milk, its odor, taste, etc., carefully 
noted in each case. 

The tubes are then again heated in the tank at the same tem- 
perature as before, for another six hours, when observations of 
the appearence of the milk in each tube are once more taken. The 
tainted milk may then easily be discovered by the abnormal 
coagulation of the sample. According to Gerber,^ good and prop- 
erly handled milk should not coagulate in less than twelve hours, 
when kept under the conditions described, and should not show 
anything abnormal when coagulated. Milk from sick cows and 
from cows in heat, or with diseased udders, will always coagulate 
in less than twelve hours. If the milk does not curdle within a day 
or two, it should be tested for preservatives (299). 

157. The Monrad rennet test is used by cheese mak- 
ers for determining the ripeness of milk. Fig. 48 shows 
the apparatus used in the test. 5 cc. of rennet extract 
is measured into a 50 cc. flask by means of a pipette; 
the pipette is rinsed with water, and the flask filled to 
the mark with water. 160 cc. of milk is now measured 
into the tin basin from the cylinder and slowly heated 
to exactly '86° F. 5 cc. of the dilute rennet solution is 



^ Die praktische Milchpriifung, p. 85. 



Testing Milk on the Farm. 



141 



then quickly added to the warm milk and the time 

required for coagulation 
noted. ^ Milk sufficiently ripe 
for Cheddar cheese making 
will coagulate in 30 to 60 
seconds, according to the 
strength of the rennet ex- 
tract used. 

158. The Marschall ren- 
net test is used for the same 
purpose as the Monrad test. 
The directions for this test 
are as follows: Fill the small 
glass with pure water to 
the mark, pour into it one 
cc. of rennet extract and 
rinse the pipette in the same 
water. Fill the cup with 

milk to the zero mark, add the rennet, mix thoroughly 

and allow it to stand. The sweeter the milk is, the 

longer it \vill take to 

coagulate, and the more 

milk will run out of the 

cup before the point of 

coagulation is reached, 

when the flow of milk 

will cease. The time re- 
quired for coagulatinj.' 

the milk is shown di- 

• 1 -1 1 .1 Fig. 4i). The Marschall rennet test. 

rectly by a scale on the 

inside wall of the cup (see fig. 49). 




Fig. 48. The Monrad rennet test. 




» Decker. Cheese Making. Revised ed., 1909 p. 39. 



CHAPTER IX. 
TESTING MILK ON THE FARM. 

159. Variations in milk of single cows. The varia- 
tions in the tests of milk of single cows from milking to 
milking or from day to day, are greater than many 
cow-owners suspect. There seems to be no uniformity 
in this variation, except that the quality of the milk 
produced generally improves with the progress of the 
period of lactation; even this may not be noticeable, 
however, except when the averages of a number of tests 
made at different stages during the lactation period are 
compared with each other. ^Vlien a cow gives her maxi- 
mum quantity of milk, shortly after calving, the qual- 
ity of her milk is generally poorer (by one per cent, of 
fat or less) than when she is drying off. Strippers' 
milk is therefore, as a rule, richer in fat than the milk 
of fresh cows. 

160. By testing separately every milking of a number 
of cows through their whole period of lactation, the 
results obtained have seemed to warrant the following 
conclusions in regard to the variations in the test of the 
milk from single cows, and it is believed that these con- 
clusions allow of generalization.^ 

1. Some cows yield milk that tests about the same at 
every milking, and generally give a uniform quantity 
of milk from day to day. 

^ Illinois experiment station, bulletin 24. 



Testing MUk on the Farm. 143 

2. Other cows give milk that varies in an unexplain- 
able way from one milking to another. Neither the 
morning nor the evening milking is always the richer, 
and even if the interval between the two milkings is 
exactly the same, the quality as well as the quantity of 
milk produced will vary considerably. Such cows are 
generally of a nervous, excitable temperament, and are 
easily affected by changes in feed, drink, or surround- 
ing conditions. 

3. The milk of a sick cow, or of a cow in heat, as a 
rule, tests higher than when the cow is in normal con- 
dition; the milk yield generally decreases under such 
conditions; marked exceptions to this rule have, how- 
ever, been observed. 

4. Half-starved or underfed cows may give a small 
yield of milk testing higher than when the cows are 
properly nourished, probably on account of an accom- 
panying feverish condition of the animal. The milk is, 
however, more generally of an abnormally low fat con- 
tent, which may be readily increased to the normal per 
cent, of fat by liberal feeding. 

5. Fat is the most variable constituent of milk, while 
the solids not fat vary within comparatively narrow 
limits. The summary of the analyses of more than 2400 
samples of American milk calculated by Cooke^ shows 
that while the fat content varies from 3.07 to 6.00 per 
cent., that of casein and albumen varies only from 2.92 
to 4.30 per cent., or less than one and one-half per cent.. 

1 Vermont experiment station, report for 1890, p. [)i : Woll's Hand- 
book for Farmers and Dairymen, Fifth ed., p. 250. 



144 Testing Milk and Its Products. 

and the milk sugar and ash content increases but little 
(about .69 per cent.) within the range given. 

6. A test of only one milking may give a very erro- 
neous impression of the average quality of a certain 
cow^s milk. A composite sample (see 179) taken from 
four or more successive milkings will represent the 
average quality of the milk which a cow produces at 
the time of sampling. 

i6i. The variations that may occur in testing the 
milk of single cows, are illustrated by the following fig- 
ures obtained in an experiment made at the Illinois ex- 
periment station/ in which the milk of each of six cows 
was weighed and analyzed daily during the whole period 
of lactation. Among the cows were pure-bred Jerseys, 
Shorthorns and Holsteins, the cows being from three to 
eight years of age and varying in weight from 850 to 
1350 lbs. During a period of two months of the year- 
the cows were fed a heavy grain ration consisting of 
twelve lbs. of corn and cob meal, six lbs. of wheat bran, 
and six lbs. of linseed meal, per day per head. This sys- 
tem of feeding was tried for the purpose of increasing, 
if possible, the richness of the milk. The influence of this 
heavy grain feed, as well as that of the first pasture 
grass feed, on the quality and the quantity of the milk 
produced is shown in the following table, which gives 
the complete average data for one of the cows (No. 3). 
The records of the other cows are given in the publica- 
tion referred to ; they were similar to the one here given 
in so far as variations in quality are concerned. 

» Bulletin 24. 

= See 175. 



Testing Milk on the Farm. 



145 



Average results obtained in weighing and testing a cow's 
milk daily during one period of lactation. 



MONTH 



Si 

4) — 

> 



December ! 920 

January ! 927 

February I 1035 

March \ 1047 

April [ 1054 

May 1079 

June 1105 

July- 1180 

AuK-ust I 1130 



Daily milk 


Test ol 




Yield of f 




yield 




one day's milk 


per day 


? 


+j 




? . 


+3 . 




© 


+j 


bo 




cw 


bt*i 


^*^ 


Ui*^ 


bi 


V) 






<D ,/ 


a o 


^o 


0) o 


d . 




> 


si £ 


o— 


Aver 
per 


"S'S 


c 0) 


Hi—. 

> 


tia 


< 


-H 


hJ 


pqM 


iJO 


m 


12.1 


10.0 


10.0 


3.8 


4.9 


3.0 


.46 


.60 


16.0 


17.7 


14.0 


3.7 


4-6 


2.7 


.59 


.76 


16.1 


17.7 


13.5 


3.6 


5.8 


3.2 


.58 


.84 


' 14.3 


16.0 


12.5 


3.8 


4.7 


3.4 


.54 


.61 


13.8 


16.5 


11. 5 


! 4.0 


5.8 


3.0 


.55 


.72 


14.5 


17 2 


10.0 


i 3.8 


4.6 


3.4 


.55 


.70 


, 12- 1 


14.0 


9.2 


i 3.9 


4.6 


3.2 


.47 


.57 


9.3 


12.2 


6.0 


1 4.2 


6.2 


2.8 


.39 


.60 


1 G.4 


9.3 


35 


! *-7 


7.9 


2.9 


.30 


.50 



.34 
.44 
.51 

.50 
.46 
.44 
.35 

.27 
.16 



162. The average test of this cow's milk for her whole 
period of lactation was 3.8 per cent, of fat (i. e., the 
total quantity of fat produced -^- total milk yield X 
100) ; twice during this time the milk of the cow tested 
as high as 5.8 per cent., and once as low as 2.7 per cent. 
The average weight of milk produced per day by the 
cow was 14 lbs. ; this multiplied by her average test, 
3.8, shows that she produced on the average .53 lb., or 
about one-half of a pound, of butter fat per day during 
her lactation period. If, however, her butter-producing 
capacity had been judged by the test of her milk for 
one day only, this test might have been made either on 
the day when her milk tested 5.8 per cent,, or when it 
was as low as 2.7 per cent. Both of these tests were 
made in mid-winter when the cow gave about 16 lbs. of 
milk a day. Multiplying this quantity by .058 gives .93 
lb. of fat, and by .027 gives .43 lb. of fat. Either 

10 



146 Testing Milk and Its Products. 

result would show the butter fat produced by the cow on 
certain days, but neither gives a correct record of her 
actual average daily performance for this lactation 
period. 

A sufficient number and variety of tests of the milk 
of many cows have been made to prove that there is 
no definite regularity in the daily variations in the 
richness of the milk of single cows. The only change in 
the quality of milk common to all cows is, as stated, 
the natural increase in fat content as the cows are dry- 
ing off, and even in this case the improvement in the 
quality of the milk sometimes does not occur until the 
milk yield has decreased very materially. 

163. Causes of variations in fat content. The qual- 
ity of a cow's milk is, as a rule, decidedly influenced by 
the following conditions: 

Length of interval between milkings. 

Change of feed. 

Change of milkers. 

Rapidity of milking. 

Exposure to rain or bad weather. 

Rough treatment. 

Unusual excitement or sickness. 

164. Disturbances like those enumerated frequently 
increase the richness of the milk for one, and some- 
times for several milkings, but a decrease in quality fol- 
lows during the gradual return to normal conditions, 
and taken as a whole there is a considerable falling off 
in the total production of milk and butter fat by the 
cow, on account of the nervous excitement which she 
has gone through. Aside from changes due to well- 



Testing Milk on the Farm. 147 

definable causes like those given above, the quality of 
some cows' milk will often change considerably without 
any apparent cause. The dairyman who is in the habit 
of making tests of the milk of his individual cows at 
regular intervals will have abundant material for study 
in the results obtained, and he will soon be able to tell 
from the tests made, if these are continued for several 
days, whether or not the cows are in a normal healthy 
condition or have been subjected to excitement or abuse 
in any way. 

165. Number of tests required during a period of 
lactation in testing cows. The daily records of the 
six cows referred to on page 142 furnish data for com- 
paring their total production of milk and butter fat dur- 
ing one period of lactation, as found from the daily 
weights and tests of their milk, with the total amount 
calculated from weights and tests made at intervals of 
7, 10, 15 or 30 days. The averages of- all results ob- 
tained with each of the six cows show' that weighing and 
testing the milk of a cow every seventh day gave 98 per 
cent, of the total milk and butter fat, which according 
to her daily record was the total product. Tests made 
one day every two weeks gave 97.6 per cent, of the 
total milk, and 98.5 per cent, of the total butter fat, 
and tests made one day per month, or only ten times 
during the period of lactation, gave 96.4 per cent, of 
the total milk, and 97 per cent, of the total production 
of butter fat. 

166. The record of one of the cows ^vill show how 
these calculations are made: It was found from the 
daily weights and tests that cow No. 1, in one lactation 
period of 307 days, gave 5,044 lbs. of milk which con- 



148 



Testing Milk and Its Products. 



tained 254 lbs. of butter fat. Selecting every thirtieth 
day of her record as testing day, the total production of 
milk and fat is shown to be as follows: 



Production of milk and hutter fat per day. 



Testing day 


Weight of milk 


Test of Milk 


Yield of butter fat 


Nov. 4 

Dec. 4 


Lbs. 
20.5 
18.7 
17.7 
20.0 
18.2 
19.5 
17.7 
13.1 
12.2 
3.2 


Per cent. 
4.7 
4.6 
4.9 
4.5 
4.7 
4.4 
4.8 
5.5 
6.2 
7.2 


Lbs. 

.96 

.86 


Jan. 3 


.86 


Feb. 2 

Mar. 3 

April 2 __ 


.90 
.86 
.81 


May 2 

June 1 _ _ _ . 


.85 

.72 


July 1 

July 31 


.76 
.23 






Total 


160.8 lbs. 
16.08 lbs. 


4.85 


7.81 lbs. 


Average per day_. 


.78 lb. 



The average - daily production of the cow, according 
to the figures given in the preceding table, was about 
16 lbs. of milk, containing .78 lb. of butter fat. Multi- 
plying these figures by 307, the member of days during 
which the cow was milked, gives 4,912 lbs. of milk and 
240 lbs. of fat. This is 132 lbs. of milk and 14 lbs. of 
fat less than the total weights of milk and butter fat, as 
found by the daily weights and tests, or 2.8 and 5.5 per 
cent, less, for milk- and fat production, respectively. 
This is, however, calculated from only ten single weights 
and tests, while it required over 600 weighings and 300 
tests of the milk to obtain the exact amount. 

Similar calculations from the records of the other 
cows gave fully as close results, showing that quite sat- 



Testing Milk on the Farm. 149 

isfactory data as to the total production of milk and 
butter fat of a cow may be obtained by making correct 
weighings and tests of her full day's milk once every 
thirty days. 

i66a. Official tests of dairy cows. The various ex- 
periment stations conduct tests of dairy cows for breed- 
ers and farmers, by which means records of production 
of milk and butter fat are obtained for periods of 7 or 
30 days, or for an entire year. This system of official 
testing is described in bulletins issued by several sta- 
tions.^ 

167. When to test a cow. The Vermont experi- 
ment station for several years made a special study of 
the question w^hen a cow should be tested in order to 
give a correct idea of the whole year's production, when 
only one or two tests are to be made during the lacta- 
tion period.- The results obtained may be briefly sum- 
marized as follows: 

a. As to quality of milk produced. If two tests of 
each cow's milk are to be made during the same lacta- 
tion period, it is recommended to take composite sam- 
ples at the intervals given below. 



SECOND SAMPLE 



For spring cows, 6 weeks after calving 6V>-7^ mos. after calving 
For summer " \8 '' '' '' 6 -7 '' " '' 

For fall *' 8-10'' " '' SVo-T " '' '* 

If only one test is to be made, approximately correct 
results may be obtained by testing the milk durinjr the 

1 See. e. p.. Wis. exp. station bull. 191 and 242 : also bull. 226. The 
Wisconsin Dairy Cow Competition, and research bull. 26, Studies In 
Dairy Production, published by this station. 

* Sixth report, 1882, p. 106; Ninth report, 1895, p. 176. 



150 



Testing Milk and Its Products. 



sixth month from calving, in case of spring cows; dur- 
ing the third to fifth month in case of summer-calving 
cows, and during the fifth to seventh month for fall- 
calving cows. 

In all cases composite samples of the milk for at least 
two days should be taken (169). "The test of a single 
sample, drawn from a single milking or day, will not of 
necessity, or indeed usually, give trustworthy results." 
b. As to quantity of milk produced. The milk may 
be weighed for two days in the middle of the month, 
and the entire month's yield obtained with considerable 
accuracy (barring sickness and drying off), 
by multipljdng the sum by a factor, ac- 
cording to the number of days in the dif- 
ferent months. The weighing is read- 
ily done by means of a spring balance, the 
hand of which is set back so that the empty 
pail brings it to zero (fig. 50). If several 
pails are to be used, they should first be 
made to weigh the same by putting a little 
solder on the lighter pails. Milk scales 
which weigh and automatically register the 
yield of milk from twenty cows have been 
placed on the market, but so far as known 
have not proved satisfactory. 
i68. Sampling milk of single cows. In sampling 
the milk of single cows, all the milk obtained at the 
milking must be carefully mixed, by pouring it from 
one vessel to another a few times, or stirring it thor- 
oughly by means of a dipper moved up and down, as 
well as horizontally, in the pail or can in which it is 




Fig. 5u. Alilk 
scale. 



Testing Milk on the Farm. 151 

held; a sample for testing purposes is then taken at 
once. A correct sample of a cow's milk cannot be ob- 
tained by milking directly into a small bottle from one 
teat, or by filling the bottle with a little milk from each 
teat, or by taking some of the first, middle and last milk 
drawn from the udder. Such samples cannot possibly 
represent the average quality of the milk of one entire 
milking, since there is as much difference between the 
first and the last portions of a milking, as between milk 
and cream. ^ Lack of care in taking a fair sample is 
the cause of many surprising results obtained in testing 
the milk of single cows. 

169. Composite samples. When a cow is to be tested 
for milk production she should be milked dry the last 
milking previous to the day when the test is to be made. 
The entire quantity of milk obtained at each^ milking is 
mixed and sampled separately. On account of the vari- 
ations in the composition of the milk, a number of tests 
of successive milkings must be made. As this involves 
considerable labor, the plan of taking composite samples 
is preferable ; the method of composite sampling and test- 
ing is explained in detail under the second subdivision of 
Chapter X (180) ; suffice it here to say that the method 
followed in the case of single cows' or herd milk is to 
take about an ounce of the thoroughly mixed milk of 
each milking; this is placed in a pint or quart glass jar 
containing a small quantity of some preservative, prefer- 
ably about half a gram (8 grains) of powdered 
potassium bi-chromate. If a number of composite sam- 
ples of the milk of single cows are taken, each jar should 

* Agricultural Science, 6, pp. 540-42. 



152 Testing Milk and Its Products. 

be labeled with the number or name of the particular 
cow. Composite tests are generally taken for two or four 
days or for a week. If continued for a week, the jars will 
contain at the end of this time a mixture of the milk 
of fourteen milkings. The composite sample is then 
carefully mixed by pouring it gently a few times from 
one jar to another, and is tested in the ordinary man- 
ner. The result of this test shows the average quality 
of the milk produced by the cow during the time the 
milk was sampled. 

As the amounts as well as the quality of the milk pro- 
duced by single cows vary somewhat from day to day 
and from milking to milking, it is desirable in testing 
single cows, especially when the test includes only a few 
days, to take a proportionate part (an aliquot) of each 
milking for the composite test sample. This is easily 
done by means of a Scovell sampling tube, the use of 
which is explained in another place (183), or by a 25 cc. 
pipette divided into ^ly cc. ; in using the latter appara- 
tus as many cubic centimeters and tenths of a cubic 
centimeter of milk are conveniently taken each time for 
the composite sample as the weight of milk in pounds 
and tenths of a pound produced by the cow.^ 

170. Testing warm milk. The opinion is some- 
times expressed that a considerable error is intro- 
duced by measuring out milk warm from the cow 
for the Babcock test, since milk expands on being 
warmed, and a too small quantity is obtained in 
this manner. By calculation of the expansion of 
milk between different temperatures it is found that 

^ Decker, Wis. experiment station, report 16, p. 155. 



Testing Milk on the Farm. 153 

1 cc. of milk at 17.5° C. (room temperature) will 
have a volume of 1.006289 cc. at 37° C. (blood-heat), 
i. e., an error of less than .03 per cent, is introduced by 
measuring out milk of ordinary quality at the latter 
temperature. While the temperature has therefore prac- 
tically no importance, the air incorporated in the milk 
during the milking process will introduce an appreci- 
able error in the testing, and samples of milk should 
therefore be left for an hour or more after milking be- 
fore the milk is measured into the test bottles. By this 
time the specific gravity of the samples can also be cor- 
rectly determined (113). 

171. Size of the testing sample. Four ounces are a 
sufficient quantity for a sample of milk if it is desired 
to determine its per cent, of fat only ; if the milk is to 
be tested with a lactometer, when adulteration is sus- 
pected, about a pint sample is needed. If this sample of 
milk is put into a bottle and carried or sent away from 
the farm to be tested, the bottle should be filled with piilk 
clear up to the neck to prevent a partial churning of 
butter in the sample during transportation (30). 

172. Variations in herd milk. While considerable 
variations in the quality of the milk of single cows are 
often met with, a mixture of the milk of several cows, 
or of a whole herd, is comparatively uniform from day 
to day; the individual differences tend to balance each 
other so that variations, when they do occur, are less 
marked than in case of milk of single cows. There are, 
however, at times marked variations also in the test of 
herd milk on successive days ; the following figures from 
the dairy tests conducted at the World's Columbian Ex- 



154 



Testing Milk and Its Products. 



position in Chicago in 1893 illustrate the correctness of 
this statement. The tests included twenty-five Jersey 
and Guernsey cows each and twenty-four Shorthorn 
cows. 

Tests of herd mUk on successive days. 



Date 


Jersey 


Guernsey 


Shorthorn 


July 16, 1893 

July 17, 1893 

July 18, 1893 

July 19, 1893 

July 20, 1893 


4.8 per cent. 

5.0 '' 

4.7 

4.6 

5.0 


4.6 per cent. 
4.5 '' 

4:.4: " 

4.6 
4.5 


3.8 per cent. 
3.8 '' 
3.8 '' 
3.7 

3.8 



On July 17, 1893, the mixed milk of the Jersey cows 
tested two-tenths of one per cent, higher than on the 
preceding day ; the Guernsey herd milk tested one-tenth 
of one per cent, lower, while the Shorthorn milk did not 
change in composition; comparing the tests on July 19 
and 20, we find that the Jersey and Shorthorn milk 
tested four-tenths and one-tenth of one per cent, higher, 
respectively, on the latter day than on the former, and 
the Guernsey milk tested one-tenth of one per cent, 
lower. There was no change in the feed of the cows or 
in the method of handling them on these days. 

173. Ranges in variations of herd milk. According 

to Fleischmann,^ the composition of herd milk will vary 

on single days from the average values for the year, 

expressed in per cent, of the latter, as follows: 

The specific gravity (expressed in degrees) may go above or 
below the yearly average by more than 10 per cent. 

The per cent, of fat may go above or below the yearly aver- 
age by more than 30 per cent. 

1 Book of the Dairy, p. 32. 



Testing the Purity of Milk. 155 

The per cent, of total solids may go above or below the yearly 
average by more than 14 per cent. 

The per cent, of solids not fat may go above or below the 
yearly average by more than 10 per cent. 

To illustrate, if the average test of a herd during a whole 
period of lactation is 4.0 per cent., the test on a single day may 
exceed 4.0+ ■\l\^ X 4.0=5.2, or may go below 2.8 per cent, (viz., 
*-0— imi X4.0); if the average specific gravity is 1.031 (lacto- 
meter degrees, 31)^ the specific gravity of the milk on a single 
day may vary between 1.0279 and 1.0341 (31+ i^jf], X 31=34.1; 
31-/o':,X31=27.9). 

174. Influence of heavy grain-feeding on the qual- 
ity of milk. If cows are not half-starved or underfed, 
an increase in the feeding ration will not materially 
change the richness of the milk produced ; this has been 
shown by numerous careful feeding experiments con- 
ducted under a great variety of conditions and in many 
countries. Good dairy cows will almost invariably give 
more milk when their rations are increased, so long as 
they are not overfed, but the milk will remain of about 
the same quality after the first few days are passed as 
before this time, provided the cows are in good health 
and under normal conditions. Any change in the feed 
of cows will usually bring about an immediate change 
in the fat content of the milk, as a rule increasing it to 
some extent, but in the course of a few days, when the 
cows have become accustomed to their new feed, the fat 
content will again return to its normal amount. 

175. The records of the cows included in the feeding 
experiment at the Illinois station, to which reference 
has been made on p. 144, furnish illustrations as to the 
effect of heavy feeding on the quality of milk. The 

1 See page 103. 



156 Testing Milk and Its Products. 

feed, as well as the milk of the cows, was weighed each 
day of the experiment. During the month of December 
each cow was fed a daily ration consisting of 10 lbs. ot 
timothy hay, 20 lbs. of corn silage and 2 lbs. of oil meal ; 
the table on p. 145 shows that cow No. 3 produced on 
this feed an average of 12.1 lbs. of milk, testing 3.8 per 
cent, of fat. In January the grain feed was gradually 
increased until the ration consisted of 12 lbs. of timothy 
hay, 8 lbs. of corn and cob meal, 4 lbs. of wheat bran, 
and 4 lbs. of oil meal. All the cows gained in milk on 
this feed ; cow No. 3 thus gave an average of 4 lbs. more 
milk per day in January than in December, but the 
average test of her milk was 3.7 per cent., or one-tenth 
of one per cent, lower than during the preceding month. 
The heavy grain-feeding was continued through Febru- 
ary and March, when it reached 12 lbs. of timothy hay, 
12 lbs. of corn and cob meal, 6 lbs. of wheat bran and 
6 lbs. of oil meal per day. The records show that the 
flow of milk kept up to 16 lbs. per day in February in 
case of this cow, but fell to 14 lbs. in March and April, 
the average test of the milk being, in February 3.6, in 
March 3.8, and in April 4.0 per cent. The milk was, 
therefore, somewhat richer in April than in December, 
but not more so than is found normally, owing to the 
progress of the period of lactation. 

176. Influence of pasture on the quality of milk. 
On May 1, the cows were given luxuriant pasture feed 
and no grain ; a slight increase in the average amount of 
milk produced per day followed, with a reduction in 
the test, this being 3.8 per cent., the same as in De- 
cember. 



Testing Milk on the Farm. 157 

During all these changes of feed there was, therefore, 
not much change in the richness of the milk, while the 
flow of milk was increased by the heavy grain feeding 
for several months, as well as by the change from grain- 
feeding in the barn to pasture feed with no grain.^ As 
a general rule, the test of the milk will be increased by 
a few tenths of a per cent, during the first couple of 
weeks after the cows have been turned out to pasture 
in the spring. The increase is perhaps due as much to 
the stimulating influence of out-door life after the con- 
finement in the stable during the winter and spring, as 
to the change in the feed of the cows. After a brief 
period the milk will again change back to its normal fat 
content. 

177. The increase which has often been observed in 
the amount of butter produced by a cow, as a result of 
a change in feed, doubtless as a rule comes from the 
fact that more, but not richer milk is produced. The 
quality of milk which a cow produces is as natural to 
her as is the color of her hair and is not materially 
changed by any special system of normal feeding.^ 

1 For further data on this point, see Cornell (N. Y.) exp. sta. bulle- 
tins 13, 22, 36 and 49 ; N. D. exp. sta., bull. 16 ; Kansas exp. sta., re- 
port, 1888 ; Hoard's Daiiyman, 1896, pp. 924-5 ; W. Va. exp. sta., b. 
109. 

2 On this point numerous discussions have taken place in the past in 
the agricultural press of this and foreign countries, and the subject 
has been under debate at nearly every gathering of farmers where feed- 
ing problems have been considered. Many farmers are firm in their be- 
lief that butter fat can be "fed into" the milk of a cow, and would take 
exception to the conclusion drawn in the preceding. The results of 
careful investigations by our best dairy authorities point conclusively, 
however, in the direction stated, and the evidence on this point is over- 
whelmingly against the opinion that the fat content of the milk can be 
materially and for any length of time increased by changes in the sys- 
tem of feeding. The most conclusive evidence in this line is perhaps 



158 Testing Milk and Its Products. 

178. Method of improving the quality of milk. 

The quality of the milk produced by a herd can gener- 
ally be improved by selection and breeding, i. e., by dis- 
posing of the cows giving poor milk, say below 3 per 
cent, of fat, and by breeding to a pure-bred bull of a 
strain that is known to produce rich milk. This method 
cannot work wonders in a day, or even in a year, but it 
is the only certain way we have of improving the qual- 
ity of the milk produced by our cows. 

It may be well in this connection to call attention to 
the fact that the quality of the milk which a cow pro- 
duces is only one phase of the question ; the quantity is 
another, and an equally important one. Much less dis- 
satisfaction and complaint about Ioav tests among pat- 
rons of creameries and cheese factories would arise if 
this fact was more generally kept in mind. A cow giv- 
ing 3 per cent, milk should not be condemned because 
her milk does not test 5 per cent. ; she may give twice 
as much milk per day as a 5 per cent cow, and will 
therefore produce considerably more butter fat. The 
point whether or not a cow is a persistent milker is also 
of primary importance ; a production of 300 lbs. of but- 
ter fat during a whole period of lactation is a rather 
high dairy standard, but one reached by many herds, 

the Danish co-operative cow-feeding experiments, conducted during the 
nineties with over 2,000 cows in all. The conclusion arrived at by the 
Copenhagen experiment station, under whose direction the experiments 
have been conducted, is : that the changes of feed made in the different 
lots of cows included on the experiments had practically no influence 
on the chemical composition (the fat content) of the milk produced. In 
these experiments grain feeds were fed against roots, oil cake, wheat 
bran or shorts ; grain and oil cake were furthermore fed against roots, 
and roots were given as an additional feed to the standard rations 
tried, — in all ca-se." with practically negative results so far as changes 
in the fat contents of the milk produced are concerned. 



Testing Milk on the Farm. 159 

as the average for all mature cows in the herd. 
It should Le remembered that a high production of but- 
ter fat in the course of the whole period of lactation is 
of more importance than a very high test. 



Questions. 

1. How does the test of the milk yielded by a cow generally 
change with the advance of the period of lactation? 

2. Mention at least six causes of variations in the test of a 
cow's milk. 

3. How is an accurate sample taken of a cow's milk? 

4. Between which limits is the test of milk of single cows 
and of a herd likely to vary? 

5. Will it introduce any error in the. test of a cow's milk to 
measure out the sample directly after milking ?If so, how much? 

6. How many times should the milk of a cow be weighed and 
tested to calculate the total production of milk and butter fat 
by the cow during a whole period of lactation? 

7. What is an oflBcial test of a cow? 

8. How does the test, as a general rule, change during the 
first couple of weeks after the cows are let out on pasture in the 
the spring? 

9. How do changes in the feed of a cow influence the quan- 
tity and the quality of her milk? 



CHAPTER X. 

COMPOSITE SAMPLES OF MILK. 

179. Shortly after milk testing had been introduced 
to some extent in creameries and cheese factories, it was 
suggested by Patrick, then of the Iowa experiment sta- 
tion,^ that a great saving in labor, without affecting 

the accuracy of the 
results, could be ob- 
tained by testing a 
mixture of the daily 
samples of milk from 
one source, instead of 
each one of these 
samples. Such a mix- 
ture is called a com- 
posite sample. The 
usual methods of tak- 
ing such samples at 
creameries and cheese 
factories are as fol- 
lows: 

180. Methods of 
taking composite 
samples, a. Use of 




Fig. 51. Taking test samples at in-take. 



tin dipper. Either pint or quart fruit jars, or milk bot- 
tles provided with a cover, are used for receiving the 
daily samples. One of these jars is supplied for each 



1 Bulletin 9, May 1890. 



Composite Samples of Milk. 161 

patron of the factory and is labeled with his name or 
number. A small quantity of preservative (bi-chromate 
of potash, corrosive sublimate, etc., see 190) is added to 
each jar; these are placed on shelves or somewhere 
within easy reach of the operator who inspects and 
weighs the milk as it is received at the factory. When 
all the milk delivered by a patron is poured into the 
weighing can and weighed, a small portion thereof, 
usually about an ounce, is put into the jar labeled with 
the name or number of the patron. The samples are 
conveniently taken by means of a small tin dipper hold- 
ing about an ounce. This sampling is continued for a 
week, ten days, or sometimes two weeks, a portion of 
each patron's milk being added to his particular jar 
every time he delivers milk. A test of these composite 
samples takes the place of separate daily tests and gives 
information regarding the average quality of the milk 
delivered by each patron during the period of sampling. 
The weight of butter fat which each patron brought 
to the factory in his milk during this time, is obtained 
by multiplying the total weight of milk delivered dur- 
ing the sampling period by the test of the composite 
sample, dividing the product by 100. 

i8i. This method of taking composite samples has 
been proved to be practically correct. It is absolutely 
correct only when the same weight of milk is delivered 
daily by the patron. If this is not the case, the size of 
the various small samples should bear a definite relation 
to the milk delivered; one sixteen-hundredth, or one 
two-thousandth of the amount of milk furnished should, 
for in.stance, be taken for the composite sample from 

11 



.162 Testing Milk mid Its Products. 

each lot of milk. This can easily be done by means of 
special sampling devices (see 182 et seq.). As the quan- 
tities of the milk delivered from day to day by each 
patron vary but little, perhaps not exceeding 10 per 
cent, of the milk delivered, the error introduced by 
taking a uniform sample, e. g., an ounce of milk, each 
time is, however, small and it may not be necessary to 
take cognizance of it in factory work. This method of 
composite sampling described is quite generally adopted 
in separator creameries and cheese factories, where the 
payment for the milk is based on its quality. 

In order to obtain reliable results by composite sam- 
pling it is essential that each lot of milk sampled shall 
be sweet and in good condition, containing no lumps of 
curdled milk or butter granules. The milk should of 
course always be evenly mixed before the sample is 
taken. 

182. b. Drip sample. Composite samples are some- 
times taken at creameries and cheese factories by col- 
lecting in a small dish the milk that drips through a 
fine hole in the bottom of the conductor spout through 
which the milk runs from the weighing can to the re- 
ceiving vat or tank. A small portion of the drip col- 
lected each day is placed in the composite sample jar, 
or the quantity of drip is regulated so that all of it 
may be taken. In the latter case the quantity of milk 
delivered will enter into the composite sampling as well 
as its quality and the sample from, say 200 lbs. of milk, 
will be twice as large as the sample from 100 lbs. of milk. 

Where it is desired to vary the size of samples accord- 
ing to the quantity of milk delivered from day to day, 



Composite Samples of Milk. 163 

it is necessary to adopt the method of collecting drip 
samples just explained, or to make use of special sam- 
pling devices, like the *'milk thief," the Scovell, Equity, 
McKay, and Michels sampling tubes.^ The 
principle of these tubes is the same, and it wil] 
be sufficient to describe here only a few of them. 
183. c. The Scovell sampling tube. This 
convenient device for sampling milk^ (fig. 52) 
consists of a drawn copper or brass tube, one- 
half to one inch in diameter ; it is open at both 
ends, the lower end sliding snugly in a cap pro- 
vided with three elliptical openings at the side, 
through which the milk is admitted. The milk 
to be sampled is poured into a cylindrical pail, 
or the factory weighing can, and the tube, with 
the cap set so that the apertures are left open, 
is lowered into the milk until it touches the 
bottom of the can. The tube will be filled in- 
stantly to the level of the milk in the can and 
is then pushed down against the bottom of the 
can, thereby closing the apertures of the cap 
and confining within the tube a column of milk scoveii 

milk 

representing exactly the quality of the milk sampling 
in the can and forming an aliquot part thereof. 
The milk in the sampling tube is then emptied into the 
composite sample jar by turning the tube upside down. 

^A recent Wisconsin law (Chap. 99, laws of 1907) provides tli.it i'l 
pamplins cream or milk from which composite tests are to be made 
to determine the per cent of butter fat therein, no su''h sampling 
shall be lawful, unless a sample be taken from each weighinp:. and the 
quantity thus used shall be proportioned to the total weight of crenm 
or milk tested. 

' Kentucky experiment station. 8th report, pp. xxvl-xxvii. 



164 Testing Milk and Its Products. 

184. If the diameter of the sampling pail used is 8 
inches, and that of the sampling tube V2 inch, the quan- 
tity of milk secured in the tube will always stand in the 
ratio to that of the milk in the pail, of (1/2)' to 8^,^ 
that is, as 1 to 256, no matter how much or how little 
milk there is in the pail, the sample will represent 2^6 
part of the milk. For composite sampling of the milk 
of single cows, this proportion will prove about ri^ht; 
if more milk is wanted for a sub-sample, dip twice, or 
pour the milk to be sampled into a can of smaller diam- 
eter. If the mixed milk from a number of cows is to 
be sampled, a wider sampling can may be used. By ad- 
justing the diameter of the tube or the can, any de- 
sired proportion of milk can be obtained in the sample. 

For factory sampling, with a weighing can 26 inches 
in diameter, a tube three-quarters of an inch in diameter 
will be found of proper dimensions. 

In using these tubes, the milk or cream must in all 
cases be in cylindrical cans when the sample is drawn. 

The sampling tube will furnish a correct sample of 
the milk in the can, even if this has been left standing 
for some time; it is better, however, to take out the 
sample soon after the milk has been poured into the can, 
as the possible error of cream adhering to the sides of 
the sampling tube is then avoided. 

185. The accuracy of the sampling of milk by means 
of the Scovell tube was proved beyond dispute in the 
breed tests conducted at the World's Columbian Expo- 

1 The contents of a cylinder are represented by the formula IT r-h, r 
being the radius of the cylinder, and h its height. The relation be- 
tween two cylinders of the same height, the radii of which are R and r, 
is therefore as TTR^h to ^r'h. or as R^ to r'^ 



Composite Samples of Milk. 



165 



sition in 1893, in which tests this method was adopted 
for sampling the milk produced by the single cows and 
the different herds.^ The data obtained in these breed 
tests also furnish abundant proof of the accuracy of the 
Babcock test. 

186. Accuracy of the described methods of sam- 
pling. An experiment made at the Wisconsin Dairy 
School may here be cited, showing that concordant re- 
sults will be obtained by the use of the drip sampling 
method and the Scovell tube. Two composite samples 
were taken from fifty different lots of milk, amounting 
to about 6,000 lbs. in the aggregate. One sample was 
taken of the drip from a hole in the conductor spout 
through which the milk passed from the weighing can; 
the other was taken from the weighing can by means 
of a Scovell sampling tube. The following percentages 
of fat W' ere found in each of these samples r 



Drip composite sample 

Scovell tube composite sample 



Babcock test 



4.0 per cent. 
4.0 per cent. 



Gravimetric 
anal.vsis 

4.04 per cent. 
4.06 per cent. 



187. d. The McKay sampler (fig. 53), constructed by 
Professor G. L, McKay, formerly of Iowa experiment 
station, consists of two nickel-plated brass tubes that 
telescope one within the other; both have a milled 
slot so made that when the handles stand together the 
slot is open ; by turning the handles at right angles the 

^ Kentucky expovimont station. 8th report, pp. xxx-xxxi. Another 
form of a milk snmplins tubp in use at the Iowa experimont station 
was described and illustrated by Mr. Eckles in Breeder's Gazette, 
May 19. 1«07. 

2 See also 199 et seq. 



166 



Testing Milk and Its Froducts. 




sslot is closed. The sampler is made 
in two lengths, 21 and 18 inches, 
and has been found very convenient 
for sampling either milk or cream. 
187a. e. Michels' cream-sam- 
pling tube consists of a modified 
Scovell sampler in a tin jacket. It 
was constructed by Professor John 
Michels, late of North Carolina agri- 
cultural college. This sampler ren- 
ders possible an accurate and rapid 
sampling of any cream, regardless 
of its richness and acidity, without 
stirring the cream. 

188. f. Composite sampling with a 
"one-third sample pipette." Milk is 
sampled directly from the 
weighing can into the Babcock test bottle 
by means of a pipette hold- 
ing 5.87 cc, which is one- 
third the size of the regu- 
lar pipette. This quantity 
is measured into the test 
bottle from three successive 
lots of milk from the same 
patron and the test then 
made in the ordinary man- 
ner. In this way one test 
shows the average composi- 
tion of the milk delivered 
during three successive days 
or deliveries. When this 
method is adopted, as many 

test bottles are provided as „^^ kk n. ^ , ^.^^ 

^ r IG. 55. Test-bottle rack for use an 

there are patrons; there is no creameries and cheese factories. 




Fig. 53. The McKay coTnetimps 
sampler. sometimes 




Composite Samples of MUk. 167 

need of using any jDreservatives for milk in this case. Fig. 55 
shows a convenient rack for holding the test bottles used in com- 
posite sampling with a "one-third sample pipette." 

Accurate results can be obtained by this method of sampling, 
if care is taken in measuring out the milk, and if it is not frozen 
or contains lumps of cream. It is doubtful if the method has any 
advantage over the usual method of composite sampling. If milk 
is delivered daily and each lot is sampled with the one-third 
pipette, twice or three times the number of tests are required as 
when composite samples are taken in jars and tested once every 
week or ten days. This method furthermore takes a little more 
time in the daily sampling than the other, as the quantity of milk 
must be measured out accurately each time. If a test bottle is 
accidently broken or some milk spilled, the opportunity of ascer- 
taining the fat content of the milk delivered during the three 
days is lost; if a similar accident should occur in testing com- 
posite samples collected in jars, another test can readily be made. 

Preservatives for Composite Samples. " 

189. When milk is kept for any length of time under 
ordinary conditions, it will soon turn sour and become 
loppered, and further decomposition shortly sets in, 
which renders the sampling of the milk both difficult 
and unsatisfactory (19). The period during which milk 
will remain in an apparently sweet or fresh condition 
varies with the temperature at which it is kept, and 
with the cleanliness of the milk. It will not generally 
remain sweet longer than two days at the outside, at 
ordinary summer or room temperature. 

In order to preserve composite samples of milk in a 
proper condition for testing, some chemical which will 
check or prevent the fermentation of the milk must be 
added to it. A number of substances have been pro- 
posed for this purpose. 



168 Testing Milk and Its Products. 

190. Bichromate of potash. This preservative is 
preferred by many because it is relatively harmless, 
cheap and efficient. The bi-chromate method for pre- 
serving samples of milk was proposed by Mr. J. A. 
Alen, city chemist of Gothenburg, Sweden, in 1892,^ 
and has been generally adopted in dairy regions in this 
country and abroad. While not perfectly harmless, the 
bi-chromate is not a violent poison like other chemicals 
proposed for this purpose, and no accidents are liable 
to result from its use. 

191. The quantity of bi-chromate necessary for pre- 
serving half a pint to a pint of milk for a period of 
one or two weeks is about one-half gram (nearly 8 
grains), about one-half as much as can be placed on a 
dime. 

According to Winton and Ogden,- a .22-inch pistol 
cartridge shell % inch long, or a .32-inch caliber shell 
1/4 inch long, when loosely filled, will hold enough pow- 
dered bi-chromate to preserve % pint, and a .32-inch 
caliber shell i/o inch long will hold enough to preserve 
one pint. These shells may be conveniently handled 
by soldering to them a piece of stiff wire which serves 
as a handle. The amount of bi-chromate placed in 
each composite sample jar would fill about half the 
space representing one per cent, in the neck of a Bab- 
cock milk test bottle. 

192. The first portions of milk added to the com- 
posite sample jars containing the specified amount of 
bi-chromate will be colored almost red, but as more 

1 Biedermann's Centralblatt, 1892, p. 549. 

* Connecticut, experiment station, report for 1884, p. 222 



Composite Samples of MUk. 169 

milk is added day by day, its color will become lighter 
yellow. The complete sample should have a light straw 
color; such samples are most easily mixed with acid 
when tested. If more bi-chromate is used, the solution 
of the casein in the acid is rendered difficult and re- 
quires persistent shaking. Bi-chromate can be bought 
at drug stores or from dairy supply dealers at about 30 
cents a pound. Powdered bi-chromate of potash should 
be ordered, and not crystals, as the latter dissolve only 
slowly in the milk. Bi-chromate tablets containing the 
correct quantity of preservative for a quart or pint sam- 
ple have also been placed on the market and will be 
found convenient. 

193. Corrosive sublimate tablets for composite 
samples. During late years corrosive sublimate tablets 
have come into general use in factories. These contain 
mercuric chlorid with anilin color (rosanilin).^ The 
coloring matter is added to give a rose color to the sam- 
ple preserved, thus showing that the milk is not fit for 
consumption; the bi-chromate giving naturally a yellow 
color to the milk, renders unnecessary the addition of 
any special coloring matter. 

Compounds containing corrosive sublimate are violent 
poisons and must always be handled with the greatest 
care, lest they get into the hands of children or persons 
not familiar with their poisonous properties; they will 
preserve the milk longer than bi-chromate when applied 
in sufficient quantities. 

Among other substances recommended for use in but- 
ter or cheese factories as milk preservatives for com- 

1 Iowa experiment station, bulletins 9, 11, 32. 



170 Testing Milk and Its Products. 

posite samples may be mentioned formaldehyde, boracic- 
acid compounds, chloroform, carbon bi-sulfid,^ copper 
ammonium sulfate, sodium fluorid and ammonia glycerin 
(sp.gr., 1.031). 

194. Care of composite samples. The composite 
sample jars should be kept covered to prevent loss by 
evaporation, and in a cool, dark place, or at least out 
of direct sunlight when bi-chromate of potash is used 
as a preservative; the chromic acid formed by the re- 
ducing influence of light on chromate solutions pro- 
duces a leathery cream which it is difficult to dissolve in 
sulfuric acid. 

A coating of white shellac has been suggested to pro- 
tect the labels of the composite sample jars. The shel- 
lac is applied after the names of the patrons have been 
written on the labels, and when these have been put on 
the jars. Gummed labels, lx2i/2 inches, answer this 
purpose well. 

Numbers are sometimes ground on the sample jar or 
stamped on brass tags attached to the jars by a wire. 

In keeping the milk from day to day, care should be 
taken that the cream forming on the milk does not stick 
to the sides of the jars in patches above the level of the 
milk. Unless the daily handling of the jars and the 
addition of fresh portions of milk be done carefully, 
the cream will become lumpy and will dry on the sides 
of the jars. In some cases it is nearly impossible to 
evenly distribute this dried cream through the entire 
sample at testing time so as to make the composite 

1 Delaware experiment station, eighth report, 1896, which also see for 
trials with a large number of different preservatives. 



Composite Samples of Milk. 171 

sample a true representative of the different lots of milk 
from which it has been taken. 

195. Every time a new portion of milk is added to 
the jar this should be given a gentle horizontal rotary- 
motion, thereby mixing the cream already formed in 
the jar with the milk and loosening the cream stick- 
ing to its side. This manipulation also prevents the 
surface of the milk from becoming covered with a layer 
of partially dried leathery cream. 

Composite samples having patches of dried cream on 
the inside of the jar are the result of carelessness or 
ignorance on the part of the operator. If proper at- 
tention is given to the daily handling of the composite 
samples, the cream formed in the jars can again be 
evenly mixed with the milk without difficulty. 

196. Fallacy of averaging percentages. A composite 
sample of milk should represent the average quality 
of the various lots of milk of which it is made up. This 
will be true if a definite aliquot portion or fraction of 
the different lots of milk is taken. If the weights of, 
say ten different lots of milk, are added together and 
the sum divided by ten, the quotient will represent the 
average weight per lot of milk, but an average of the 
tests of the different lots obtained in this way may not 
be the correct average test of the entire quantity of 
milk. The accuracy of such an average figure will de- 
pend on the uniformity in the composition and weights 
of the ten lots of milk. When there is no uniformity, 
the weights of the different lots of milk as well as their 
tests must be considered. The following example will 
illustrate the difference between the arithmetical aver- 



172 



Testing Milk and Its Products. 



agre of a number of single tests and the true average test 
of the various lots. 

Methods of calcidating average percentages. 



I. Milk 


v^arying in weig 
and tests. 


hts 


II. Milk of unifoi 
and tests 


•m weights 


Lot 




4 

o 




Lot 


la 


Tesl 
of milk. 




I 


lbs. 

120 

570 

360 

55 

82 


per ct. 

3.5 
5.0 
5.2 
3.0 
4.0 


lbs. 

4.2 

28.5 

18.7 

1.6 

3.2 


I.. 


lbs. 

250 
225 
240 
238 
234 


per ct. 

4.2 
4.0 
4.3 
4.1 
4.4 


lbs. 
10.5 


II 


II 


9.0 


Ill 


III 


10 3 


IV 


IV 


9.7 


V 


V -- 


10.3 




Total 

Average... 

True average 
test 




Total 

Average .. 

True aver- 
age test 


'1187 
237 


4.14 
4.73* 


56.2 
11.24 


1187 
237 


4.20 
4.22t 


49.8 
10.0 













»56. 2X100 



=4.73 



t49.8X100 



-=4.22 



1187 1187 

197. The figures given in the table show that when 
the different lots of milk vary in test and weight, as in 
the first case, the correct average test of the 1187 lbs. 
of milk is not found by dividing the sum of these tests 
by five, which would give 4.14 per cent. ; but by divid- 
ing 56.2 (the total amount of fat in the mixed milk) 
by 1187 (the total amount of milk), which is 4.73; 
this is the correct average test of the mixed milk made 
up of the five different lots. 

In the second case, the variations in both the weights 
of the different lots of milk and their tests, are com- 
paratively small, and both methods of calculation give 
therefore practically the same average test; but also in 
this case, the correct average test is found by dividing 



Composite Samples of Milk. 173 

the total amount of fat by the total quantity of milk, 
making 4.22 per cent., instead of 4.20 per cent., which is 
the arithmetical mean of the five tests. The quantities 
of milk in the various lots do not enter into the calcula- 
tion of the latter.^ 

198. The second example represents more nearly 
than the first one the actual conditions met with at 
creameries and cheese factories. As a rule, the mixed 
milk from a herd of cows does not vary more in total 
weight or tests, within a short period of time like one 
to two weeks, than the figures given in this example. 
On account of this fact, samples taken, for instance, 
with a small dipper may give satisfactory results to all 
parties concerned. If the different lots of milk varied 
in weight and test from day to day, as shown in the 
first case, it would be necessary to use a ''milk thief" or 
one of the sampling tubes for taking the composite 
samples; the size of each of the samples taken would 
then represent an exact aliquot portion of the various 
lots of milk (182). 

199. A patron's dilemma. The following incident will fur- 
ther explain the difficulties met with in calculating average tests 
of different lots of milk. 

The weekly composite sample of the milk supplied by a cream- 
ery patron from his herd of 21 cows tested 4,0 per cent. fat. 
One day the farmer brought to the creamery a sample of the 
morning's milk from each of his cows, and had them tested; 
after adding the tests together and dividing the sum by 21, he 
obtained an average figure of 5.1 per cent, of fat. From this 
he concluded that the average test of the milk from his cows 

1 In the experiment given on p. 148, the arithmetical mean of the 
tests is 5.15 per cent., while the true average fat content of milk 
Is 4.85 per cent. 



174 Testing Milk and Its Products. 

ought to be 5.1, instead of 4.0, and naturally asked for an ex- 
planation. 

The first thing done was to show him that while 5.1 was the 
correct average of the figures representing the tests of his 
twenty-one cows, it was not a correct average test of the mixed 
milk from all his cows, as he had not considered, in calculating 
this average, the quantities of milk yielded by each cow; the 
following illustration was used: 

Cow No. 1, yield 25 lbs. of milk, test 3-6 per cent, =0.9 lb. of butter fat. 
Cow No. 2, yield 6 lbs. of milk, test 5.0 per cent. =0.3 lb. of butter fat. 

Total 31 lbs. 2)8.6 1.2 lbs. 

4 . 3 per cent. 

The two cows gave 31 lbs. of milk containing 1.2 lbs. of fat; 
the test of the mixed milk would therefore not be 4.3 per cent. 

(^^^±^), but ^-^~P^=3.87 per cent. If the fat in the mixed 
milk was calculated by the average figure 4,3 per cent., 1.33 lbs. 
of fat would be obtained, i. e., 0.13 lb. more than the cows pro- 
duced. 

In order to further demonstrate the actual composition of the 
mixed milk of the twenty-one cows, the milk of each cow was 
weighed and tested at each of the two milkings of one day. The 
weights and tests showed that the cows produced the following 
total number of pounds of milk and of fat: 

Morning milking, 113.3 lbs. of milk, containing 5.17 lbs. of fat. 

Night milking, 130.9 lbs. of milk, containing 4.98 lbs. of fat. 

The morning milk therefore contained •^•^'^xioo --4 5g pgj. cent. 

of fat, and the night milk, i^^|^^ =3.80 per cent, of fat. 

The sum of the morning and night milkings gave: milk, 244.2 
lbs., fat 10.15 lbs. The mixed morning and night milk, there- 
fore, contained ^^-^^^-^=4.1 per cent, of fat. This is the true 

average test of the morning and night milkings of these twenty- 
one cows, as found by weighing and testing separately the milk 
of each cow at both milkings. 

The total milk was strained into a large can at the farm, both 
in the morning and in the evening. A sample of the mixed milk 
was in each case taken with a long-handled dipper as soon as 
the milkings were finished. When the cans of milk were deliv- 



Composite Samples of Milk. 



175 



ered at the creamery, a sample of each was takeai with a Scovell 
sampling tube. The tests of these four samples are given below, 
together with the results of the individual tests: 





Morning- Milk 


Night Milk 


Sample taken at the farm, with dip- 
per _ __ _ 


4.4 per cent. 

4.5 '' 
4.5 '' 


3.8 per cent. 
.3 7 " 


Sample taken at creamery with Sco- 
vell tube _ _ 


Calculated from weights and tests of 
milk from each cow 


3.8 



The figures given show that practically uniform tests were ob- 
tained by the different methods of sampling. 



Questions. 

1. What is a composite sample of milkt 

2. Describe the proper care of composite samples. 

3. Give an example showing that composite samples of milk 
may be inaccurate when taken with a small dipper. 

4. Describe the construction of the following methods of sam- 
pling milk or cream, by (a) drip sample, (b) the Scovell, (c) 
the McKay, and (d) the Michels' sampling tubes. 

5. What is the purpose of adding preservatives to milk or 
cream samples? Mention the more common preservatives used 
and quantities to be addj. 



CHAPTER XI. 
CREAM TESTING AT CREAMERIES. 

200. The cream delivered at g:athered-creara factories 
is now tested by the Babcock test in many localities, and 
this has been adopted as a basis of paying for the cream 
in the same manner as milk is paid for at separator 
creameries. It has been found to be more satisfactory 
to both cream buyer and seller than either the oil-test 
churn or the space (or gauge) systems which were pre- 
viously used for this purpose. 

The details of the application of the Babcock test to 
the practical work at cream-gathering creameries have 
been carefully investigated by Winton and Ogden in 
Connecticut,^ Bartlett in Maine,^ and Lindsey in Massa- 
chusetts,^ and we also owe to the labors of these chem- 
ists much information concerning the present workings 
of other systems of paying for the cream delivered at 
creameries. 

201. The space system. Numerous tests have shown 
that one space or gauge of cream does not contain a 
definite, uniform amount of fat. In over 100 compari- 
sons made by Winton it was found that one space of 
cream* contained from .072 to .170 lb. of butter fat, or 

1 Conn, experiment station (New Haven), bull. 108 and 119; report 
1894. pp. 214-244. 

2 Maine experiment station, bull. 3 and 4 (S. S.) 

3 Hatch experiment station, report 1894, pp. 92-103: 1895, pp. 67-70. 
*The space is the volume of a cylinder, 8% inches in diameter and 

If of an inch high. The number of spaces in each can of millt is 
read off before skimming by means of a scale marked on a strip of 
glass In I lie side of the can (Conn. exp. sta., bull. 119). 



^ 



Cream Testing at Creameries. 



177 



on the average .13 lb., and the number of spaces re- 
quired to make one pound of butter varied from 5.01 to 
11.72. It is also claimed that in the winter season when 
the cream is gathered at long intervals, like once a week, 
it is necessary for the buyer to accept the seller *s state- 
ment of the record of the number of cream spaces which 
he furnishes, since the cream cannot be left in the 
creaming can for so long a time. These objections to 
the space system apply only to the method of paying 
for the cream, and not to the manner in which the 
cream is obtained. 

202. The oil-test churn. As stated in the introduc- 
tion, the oil-test churn (fig. 56) has been used quite ex- 
tensively among gath- 
ered-cream factories ; 
this system is based on 
the number of inches 
of cream which the 
various patrons deliver 
to the factory; a 
creamery inch is the 
quantity of cream 
which will fill a can 
twelve inches wide, one 
inch high; it contains 
113 cubic inches.^ This 
quantity was supposed to make one pound of butter. 

In using this method the driver pours the patron's 
cream into his 12-inch gathering pail, measures it with 

* A layer of two inches in an 8-incb pail contains 100.531 cubic 

inches, two inches in a 8%-inch pail 110.18 cubic incties, nnd two 

inches in a 8%-inch pail 113.49 cubic inches. 
12 




Fig. 56. The oil-test churn. 



178 



Testing Milk and Its Products. 



his rule and records the depth of the cream in the can. 
in inches and tenths of an inch. The cream is then 
stirred thoroughly with a ladle or a stout dipper, and 
sampled by filling a test tube to the graduation mark 
by means of a small conical dipper provided with a 
lip. A driver's case contains either two or three 
"cards," holding fifteen test tubes each (see fig. 57) 

The tubes as filled are 
placed in the case and 
the corresponding num- 
ber in each instance re- 
corded in front of the 
patron's name, together 
with the number of 
inches of cream fur- 
nished by him. 

On the arrival at the 
creamery the tin cards 
holding the tubes are placed in a vessel filled with 
water of the churning temperature (say, 60° in summer 
and 65° to 70° in Avinter). When ready for churning 
they are placed in the oil-test churn (fig. 56), the cover 
of the churn put on, and the samples of cream churned 
to butter. On the completion of the churning, the cards 
are transferred to water of 175-190° Fahr., where they 
are left for at least ten minutes to melt the butter and 
"cook the butter milk into a curd." The oil will now 
be seen mixing through the mass. The test tubes are 
then cooled to churning temperature and churned 
again, by which process the curd is broken into fine 




Fio. 57. Cronm-gatherer's 
sample case. 



Cream Testing at Creameries. 179 

particles, which, when the butter is re-melted, will set- 
tle to the bottom. The butter is melted after the sec- 
ond churning by placing the tubes in water at 150-175° 
P., allowing them to remain therein for at least twenty 
minutes. Some samples must be churned three or four 
times before a good separation of oil is obtained. A 
clear separation of oil is often facilitated by adding a 
little sulfuric acid to the tubes. 

The length of the column of liquid butter fat is de- 
termined by means of a special rule for measuring the 
butter oil; this rule shows the number of pounds and 
tenths of a pound of butter which an inch of cream will 
make; the first tenth of a pound on the rule is divided 
into five equal parts, so that measurements may be made 
to two-hundredths of a pound. The melted fat is meas- 
ured with the rule, by raising the tin card holding the 
bottles to about the height of the eye ; the reading is 
recorded on the driver's tablet under Test per inch, op- 
posite the number of the particular patron. The test 
multiplied by the inches and tenths of an inch of cream 
supplied will give the amount of butter in pounds, with 
which the patron will be credited on the books of the 
creamery. 

203. The objection to this system of ascertaining the 
quality of cream delivered by different patrons lies in 
the fact that it determines the churnalle fat, and not 
the total fat of the cream; the amount of the former 
obtained depends on many conditions beyond the con- 
trol of the patron, viz., the consistency, acidity and tem- 
perature of the cream, the size of the churn or churn- 



180 Testing MUk and Its Products. 

ing vessel, etc.^ The same reasons which caused the 
chum to be replaced by methods of determining the 
total fat of the milk, in the testing of cows among dairy- 
men and breeders, have gradually brought about the 
abandonment of the oil test in creameries and the adop- 
tion of the Babcock test in its place. It may be said, 
on the other hand, in favor of the use of the oil test in 
creameries that it is a considerably cheaper method 
than any fat test, and takes less labor and time on the 
part of the operators than do the latter methods. 

204. The Babcock test for cream. Both the space 
system and the oil-test churn used for estimating the 
quality of cream at creameries have now largely been 
replaced by the Babcock test in the more progressive 
creameries in this country, and composite samples of 
cream are collected and tested in a similar manner as 
is done with milk at separator creameries and cheese 
factories. '' 

A very satisfactory method of arrangements for 
working the Babcock test, in use in many eastern cream- 
eries, is described by Winton and Ogden in the Con- 
necticut report previously referred • to. The cream 
gatherer who collects the cream in large cream cans is 
supplied with a spring balance (1, see fig. 58), a pail for 
sampling and weighing the cream (2), sampling tube 
(3), and collecting bottles (5). At each patron's farm 
he takes from his wagon the sampling pail and tube, 
the scales, and one small collecting bottle. He should 

* It follows from this that there can be no definite relation between 
the results obt.Tined by the Babcock test and the oil-test readings ; 
a reading of 100 in the oil-test is. however, on the average, equivalent 
to about 23 per cent, of butter fat in the cream. 



Testing Cream at Creameries. 



181 




tind in the dairy of the patron the cans of perfectly 
sweet cream, kept at a temperature of 40° to 50° F., 

and protected from dirt 
and bad odors. Either sour 
or frozen cream must be 
rejected. The patron's 
number should be painted 
in some conspicuous place 
near the cream cans in his 
dairy house. The gatherer 
hangs the scale on a hook 
near the cream to be col- 
lected; the scale should be 
made so that the hand of 

Fig. 58. Outfit for cream testing 
by the Babcock test at gathered- the dial wiU Stand at ZCrO 
cream factories. 

when the empty pail is 

hung on it. The cream is then poured at least twice 

from one can to another in order to mix it thoroughly.^ 

205. When properly mixed, the cream is poured into 

the weighing pail and is weighed and sampled. The 

authors give the following description of the cream 

sampling tube used, and directions for sampling and 

weighing the cream. 

'* Sampling Tube. — This tube is of stout brass, about Jg °^ ^^ 
inch thick, and a few inches longer than the weighing pail which 

1 The necessity of care in mixing the cream is shown by the follow- 
ing illustration given by the authors referred to. 

Per cent of fat in cream which stood for 2^ hours. 

Sample drawn 
Surface. Bottom. with sampling tube. 

Not mixed 28.00 5.00 10.25 

Poured once 23.75 22.00 22.50 

Poured twice 22.25 



182 Testing Milk and Its Products. 

IS used with it. On the upper end, a small brass stop-cock of 
the same bore is fastened. It should be nickel plated inside and 
out, to keep the metal smooth and free from corrosion. These 
tubes may be obtained from less than ~^^ to over ^ inch bore. 
The greater the diameter of the weighing pail, the wider should 
be the bore of the tube. For use with pails 8 inches in diameter, 
a j%- inch bore sampling tube will serve the purpose, but when 
the pail has a diameter of 9 or more inches, a tube with a bore 
of ^ inch or more should be used. It must be borne in mind 
that doubling the diameter of the pail, or of the sampling tube, 
increases its capacity fourfold. 

**The tube when not in use should be kept in an upright posi- 
tion to permit draining. 

'^Sampling mid Weighing. — Lower the sampling tube, cock 
end up, with the cock open, to the bottom of the weighing pail 
which holds the mixed cream. "When it is filled raise it out of 
the liquid and allow it to drain for a few seconds. By this 
means the tube is rinsed with the cream to be sampled and any 
traces of cream adhering to the tube from previous use are re- 
moved. "With the cock still open, slowly lower the sampling tube 
to the bottom of the cream pail. After allowing a moment for 
the cream to rise in the tube to the same height as in the pail, 
close the cock and raise the sampler carefully out of the cream. 
As long as the cock is closed, the cream in the tube will not 
flow out, unless the tube is strongly jarred. AUow the cream 
adhering to the outsiae of the tube to drain off for a few sec- 
onds, then put the lower end into the 1 to 1^^ oz. wide-mouth 
glass collecting bottle which bears the patron's number on its 
cork, and open the cock. The cream will then flow out of the 
sampler into the bottle, which is afterwards securely corked and 
put into the cream gatherer's case. Immediately weigh the 
cream in the cream pail to the quarter or half pound, as may 
be judged expedieait, and record the weight. 

"If the patron has more than one pailful, repeat with each 
pailful the operation of sampling and weighing, putting all the 
samples in one and the same bottle. Weigh all cream collected 
in one and the same sampling pail and draw a sample from each 
separate portion weighed. * * 



Testing Cream at Creameries. 183 

206. After sampling and weighing each patron's 
cream it is poured into the driver's large can, and the 
sample bottles are carried in a case to the creamery 
where the contents of each bottle are poured into the 
composite sample jar of the particular patron. The 
samples of cream in the small bottles, besides furnish- 
ing the means of testing the richness of the cream, give 
the creamery man an opportunity to inspect the flavor 
of each lot of cream, and the condition in which it has 
been kept by the various patrons. Some preservative, 
Visually corrosive sublimate tablets, is placed in the com- 
posite sample jars, and these are cared for and tested 
in the same manner as composite samples of milk (194). 

207. The collecting bottles should be cleaned with 
cold, and afterwards with hot water, as soon as they are 
emptied, and before a film of cream dries on them. 
When washed and dried, these bottles are placed in the 
cases, ready for the next collecting trip. There can be 
no confusion of bottles since the corks and not the bot- 
tles are marked with the numbers of the respective 
patrons. 

208. When this system of testing composite samples 
is adopted, the pattons are paid for the number of 
pounds of butter fat contained in their cream, in 
the same way as milk is paid for at separator 
creameries. It makes no difference how thick or how 
thin the cream may be, or how much skim milk is left 
in the cream when brought to the factory. Eighty 
pounds of cream containing 15 per cent, of fat is worth 
no more nor less than 48 pounds of cream testing 25 per 
cent.; in either case 12 pounds of pure butter fat is 



184 Testing Cream and Its Products. 

delivered. This will make the same amount of butter 
in either ease, viz., about 14 lbs., and both patrons 
should therefore receive the same amount of money. 

There is a small difference in the value of the two 
lots of cream to the creamery owner or the butter maker, 
in favor of the richer cream, both because its smaller 
bulk makes the transportation and handling expenses 
lighter, and because slightly less butter fat will be lost 
in the butter milk, a smaller quantity of this being ob- 
tained from the richer cream. But it is doubtful if the 
differences thus occurring are of sufficient importance 
to be noticed under ordinary creamery conditions; the 
example selected presents an extreme case of variation 
in the fat content of cream. A tl-ial of this system at 
five Connecticut creameries, supplied mostly with Cooley 
cream by over 175 patrons, showed that the average 
composition of the cream from the different patrons 
varied only from 16,9 to 19.8 per cent, of fat. The cream 
of some patrons on certain days contained only 9.5 per 
cent, of fat, and other patrons at times had as high a 
test as 30 per cent., but these great differences largely 
disappeared when the average quality of the cream 
delivered during a period of time, like a month or more, 
was considered. 

209. Smaller differences in the composition of cream 
will, however, always occur, even if the same system of 
creaming the milk, like the centrifugal process, is used 
and all factors remain as nearly the same as possible at 
all times. This is due to differences in the composition 
of the milk and its creaming quality; whether largely 
from fresh cows or from late milkers; whether kept 



Testing Cream at Creameries. 185 

standing for a time before being set, or submerged m 
the creamer immediately after milking and straining, 
diameter of creaming cans, etc. Bartlett states^ that 
the percentage of fat in the cream from the same cows 
may be increased ten per cent, or more by keeping the 
water at 70° instead of at 40° F. The higher tempera- 
ture will give the richer cream, but the separation will 
not be so complete, since a richer skim milk is obtained 
from the milk set at this temperature. Separator cream 
is not materially influenced by the conditions mentioned, 
as the separator can be regulated to deliver cream of 
nearly uniform richness from all kinds of sweet milk. 

210. At creameries where both milk and cream are 
delivered, somewhat of an injustice is done to patrons de- 
livering cream, by paying for the amounts of butter fat 
furnished by the different patrons. By multiplying the 
cream fat by 1.03,^ the value of his products to the 
creamery is taken into proper account, and justice is 
done to all parties concerned' (239). 

211. Gathering and sampling hand-separator 
cream. On account of the great variation in both the 
richness and the purity of farm separator cream it has 
been found in practice that compasite samples of cream 
are not so satisfactory to either buyer or seller as the 
testing of a sample taken from each lot of cream gath- 
ered. A still more satisfactory method is to provide 
separate cans for each patron, the cream gatherer leav- 

* Bull. 3 (S. S.>, Maine experiment station. 

" Spillman (Dairy and Creamery. Chicago, April 1, 1899) recom- 
mends the use of the factor 1.044. 

■This subject is discussed in detail in the 17th annual report of Wis. 
experiment station, pp. 90-92 ; see also the 20th report of that Station, 
pp. 130-31. 



186 Testing Milk and Its Products. 

ing an empty, clean can at each farm and taking a full 
or partially filled can of cream from the farm to the 
factory. This makes it necessary for the cream gath- 
erer to carry as many cans as he has patrons to gather 
cream from, but it gives the factory operator a chance 
to inspect, weigh and sample the cream from each farm 
and relieves the cream gatherer of all these details which 
are often the cause of dissatisfaction. 



Questions. 

1. In what ways do the results obtained with the oil- test 
churn differ from those obtained with the Babcock test? 

2. Describe the method of testing cream by the Babcock test 
at gathered-cream factories. 

3. What advantages has the gathering of cream in separate 
cans over mixing the cream from all the patrons of one route? 



CHAPTER XII. 
CALCULATION OF BUTTER- AND CHEESE VIELD 

A.— Calculation op Yield op Butter. 

212. Butter-fat test and yield of butter. The Bab- 
cock test shows the amount of pure butter fat contained 
in a sample of milk, cream or other dairy products. 
The butter obtained by churning cream or milk con- 
tains, in addition to butter fat, a certain amount of 
water, salt and curd. While an accurate milk test 
gives the total quantity of butter fat found in the sam- 
ple of milk or cream tested, the churn cannot be de- 
pended upon either to leave the same amount of butter 
fat in the butter milk or to include the same amount of 
water, salt or curd in the butter at each churning. 

If a quantity of milk, say 3,000 lbs., be thoroughly 
mixed in a vat, and then divided into half a dozen equal 
portions, a Babcock test of the different lots will show 
the same percentage of butter fat in each portion. If, 
on the other hand, each of these lots be skimmed, and 
the cream ripened in different vats and churned sepa- 
rately, the same weight of butter from each lot of 500 
lbs. of milk will not be obtained, even by the most expert 
butter maker, or if all the operations of skimming, cream 
ripening, churning, salting and butter-working were 
made as nearly uniform as possible. Careful operators 
can handle the milk and cream so that very nearly the 



188 



Testing Milk and Its Products. 



same proportion of fat contained in the milk is re- 
covered in the butter in different churnings, but since 
the water and salt in butter are held mechanically and 
are not chemically combined with it, the amounts re- 
tained by the butter are quite variable in different 
churnings. 

213. Variations in the composition of butter. As 
an illustration of the variations in the composition of 
butter that usually occur, the analyses made in the 
breed tests at the World's Fair in 1893 may be here 
cited ; the butter was in all cases made by as nearly 
identical methods and under as uniform conditions as 
could possibly be obtained by the skilled operators hav- 
ing this work in charge ; the average composition of 350 
samples of this butter, with upper and lower limits, 
was as shown in the following table: 

Composition of samples of butter, World's Fair, 1893. 



Average of 350 
analyses 

Lower and up- 
per limits 



Water 


Fat 


Curd 


Salt and 
ash 


Per cent. 

n.sr 

8.63-15.00 


Per cent . 

84.70 

76.53-88.26 


Per cent. 
.95 

.50-2.14 


Per cent. 

2.78 

1.01-8.58 



Sum of 

water, curd, 

salt and 

ash 

Per cent. 
15.80 



Analyses of fifty samples of creamery butter taken in 
1896, from the tubs ready for market at as many Wis- 
consin creameries, showed that no two of them were ex- 
actly alike in composition, but varied within the limits 
given on the following page -} 



* Wisconsin experiment station, bull. 56. 



Calculation of Butter- and Cheese Yield. 1S9 



Summary of analyses of Wisconsin creamery butter. 





Water 


Fat 


Curd 


Salt and 
ash 


Sum of 

water, curd, 

salt and 

ash 


Higrhe.st 

Lowest.. 

Average 


Percent. 

17.03 

9.18 

12.77 


Per cent. 

87 50 
77.07 
83.08 


Per cent. 

2.45 

.3d 

1.28 


Per cent. 

4.73 
1.30 

2.87 


Per cent. 

22.95 
12.50 
16.92 



The preceding analyses shew the composition of but- 
ter made at one place where every possible effort was 
taken to produce a uniform product, and of butter made 
at fifty different creameries, where there was more or 
less variation in the different operations of manufacture 
and in the appliances and machinery used. The ma- 
jority of the samples of butter analyzed, in either case, 
were very near the average composition given, but since 
there are such wide variations in the composition of the 
butter made by the uniform methods adopted in the 
World's Fair breed tests, butter of a more uniform com- 
position cannot be expected from the thousands of dif- 
ferent creameries and private dairies which supply the 
general market with butter. 

The analyses of the fifty samples of creamery butter, 
given above, show that the content of the butter fat 
varied from 77 to 87.5 per cent., and according to 
the average of the analyses, 83 pounds of butter fat was 
contained in, or made, 100 lbs. of butter. There was, 
therefore, in this case produced 20.5 per cent, more 
butter than there was butter fat, since 
83 : 100 : : 100 : x ; therefore 
100X100 



x= 



83 



rl20.5. 



190 Testing Milk and Its Products. 

214. ** Overrun" of churn over test. The yield of 
butter is not, however, as a rule compared with the 
amount of butter fat contained in the butter, but with 
the total butter fat of the whole milk or cream from 
which it was made. This ''increase of the churn over 
the test" is what is generally called overrun in cream- 
eries. 

The overrun obtained in different creameries, or even 
in the same creameries at different times, will be found 
to vary considerably. When the milk is accurately 
tested and the butter well worked, this overrun will vary 
from 10 to 16 per cent.; that is, if a quantity of milk 
contains exactly 100 lbs of butter fat, as found by the 
Babcock test or any other accurate method, from 110 to 
116 lbs. of butter ready for market will be obtained from 
it. The overrun from cream will be somewhat larger, 
18 to 22 per cent., but will never exceed 25 per cent., 
unless the butter contains less than 80 per cent, fat 
(217). 

215. Factors influencing the overrun from milk. 
Even under the very best of care and attention to de- 
tails, variations will occur in the speed of the separator, 
in the conduct of the ripening and churning processes, 
and in the condition of the butter when the churn is 
stopped; hence absolutely uniform losses of fat in skim 
milk and butter milk, or the same water- and salt con- 
tents of the butter, cannot be expected. 

The overrun in separator creameries is influenced by 
two legitimate factors : first, the losses of butter fat sus- 
tained in separating the milk and churning the cream, 
and second, the gain due to the admixture of water, 



Calculation of Butter- and Cheese Yield. 191 

salt, etc., in the manufacture of butter. Considering 
first the losses of fat in skim milk and butter milk, the 
separator will usually, when run at normal speed and 
capacity, leave the same per cent, of fat in skim milk, 
whether rich or poor milk is skimmed. An exception 
to this may be found in separating rich milk having 
large fat globules, or milk from fresh milkers, in either 
of which cases the large size of the fat globules occa- 
sions a more complete separation of fat by the centri- 
fugal force. But generally speaking, the statement 
holds good that the total loss of fat in separator skim 
milk is a factor of the quantity of milk run through the 
separator, rather than of its quality. 

216. The losses from poor, rich and average milk, as 
received at creameries and cheese factories, can be traced 
from the following statement; this gives the quantities 
of fat lost in handling milk of four grades, viz.: 2.5, 
3.5, 4.0 and 6.0 per cent., in case of each grade calcu- 
lated to a standard of 100 lbs. of fat in the milk. 

To supply 100 lbs. of fat would require the following 
amounts of the different grades of milk: 

4000 lbs. of milk testing 2.5 per cent will contain 100 lbs. of fat. 
2857 " '' '' 35 " " " 100 '' " " 

2500 " " " 4.0 " " " 100 *' *' '' 

1666 '' '' " 6.0 '' " " 100 " '' " 

Assuming that the skim milk contains .1 per cent, of 
fat and makes up 85 per cent, of the whole milk, and 
that the butter milk tests .3 per cent., and forms 10 
per cent, of the whole milk, the butter-fat record of 
the quantities of different grades of milk containing 100 
lbs. of fat will be as given in the following table. Cer- 



192 



Testing Milk and Its Products, 



tain mechanical losses are unavoidable in the cream- 
ery, as in all other factory operations, viz., milk and 
cream remaining in vats and separators, butter sticking 
to the walls of the churn, etc. These losses have been 
found to average about 3 per cent, of the total fat in 
the milk handled, under normal conditions and under 
good management (219). 

Fat available for butter in different grades of milk. 



• 

Grade of milk 


Whole 
milk 


Skim 
milk 


Butter 
milk 


0) 


Total 
loss 


Fat 

available 

for 

butter 


2.5 percent 


4000 lbs. 
2.5 per ct. 


3400 lbs. 
.1 per ct. 


400 lbs. 
.3 per ct. 

1.2 lbs. 

286 lbs. 
.3 per ct. 


Lbs. 
3.0 

3.0 

3.0 

3.0 


Lbs. 
7.6 

6.3 

5.8 

4.9 


Per ct. 


Fat. 

3.5 per cent 


100 lbs. 

2857 lbs. 
3.5 per ct. 

100 lbs. 

2500 lbs. 
4 per ct. 

100 lbs. 

1666% lbs. 
6 per ct. 


3.4 lbs. 

2429 lbs. 
. 1 per ct. 


92.4 


Fat 

4.0 per cent 


2.4 lbs. 

2125 lbs. 
.1 per ct. 


.91b. 

250 lbs. 
.3 per ct. 


93.7 


Fat. 

6.0 percent 


2.1 lbs. 

1417 lbs. 
.1 per ct. 


.71b. 

167 lbs. 
.3 per ct. 


94.2 


Fat 


100 lbs. 


1.4 lbs. 


.51b. 


95.1 



The table shows that with 2.5 per cent.-milk, there is 
a loss of 3.4 lbs. of fat in the skim milk, a loss of 1.2 
lbs. of fat in the butter milk, and of 3.0 lbs. in the 
creamery waste, for every 100 lbs. of fat in the whole 
milk, or a total loss of 7.6 lbs. from these sources. In 
case of 6 per cent, milk these losses are 1.4 lbs., .5 lb. 
and 3 lbs. for skim milk, butter milk and waste, re- 
spectively; a total loss of 4.9 lbs., or 2.7 lbs. less than 
the losses with poor milk. This difference in the losses 



Calculation of Butter- and Cheese Yield. 193 

shrinks to only .5 pound of fat in case of 3.5 and 4.0 
per cent.-milk, when a quantity containing 100 lbs. of 
fat is handled in both cases. 

The overrun from each of the four grades of milk can 
be calculated for butter containing a certain per cent, 
of fat. Assuming the fat content of butter to be 83 per 
cent, on the average (213), the quantity of butter ob- 
tained from the 100 lbs. of fat, or rather from the por- 
tion thereof which is available for butter, in each case 
will be as follows : 



UK) lbs. of fat from 


Available 
fat 


Butter cent. 
83 per ct. fat 


Overrun 


4,000 lbs. of 2.5 per cent, milk 

2,857 lbs. of 3.5 per cent, milk 

2,500 lbs. of 4.0 per cent, milk 

1,666 lbs. of 6.0 per cent, milk 


Lbs. 
92.4 
93.7 
94.2 
95.1 


Lbs. 

113.3 

113.0 

113.9 

114.6 


Per ct. 
11.3 
13.0 
13.-5 
14.6 



The overrun figures given above may be increased by 
saving some of the three pounds of butter fat lost by 
waste. If it were possible to entirely eliminate this loss 
there would be three pounds more available fat in each 
case, viz., 95.4, 96.7, 97.2, 98.1 lbs. These amounts of 
fat will make 115, 116.5, 117.1, and 118.2 lbs. butter, 
corresponding to an overrun of 15, 16.5, 17.1, and 18.2% 
from milk of the different fat contents mentioned. 

All butter makers should obtain more butter from a 
certain quantity of milk than the Babeock test shows it 
to contain butter fat, but it is impossible to know ex- 
actly, except by chemical analysis, how much butter fat 
is lost in the skim milk and the butter milk, and how 
much water, salt and curd the butter will contain. A 



194 



Testing Milk and its Products. 



butter maker's skill is shown by his ability to reduce the 
losses by waste in handling the milk, cream and butter, 
as well as the losses of butter fat in skim" milk and butter 
milk, and his carefulness in weighing, sampling and 
testing the milk, cream and butter made. 

217. Overrun from cream. The overrun from cream 
is, as already stated, larger than from milk because 
there is no loss of fat in the skim milk to be consid- 
ered. Rich cream will give a slightly larger over- 
run than thin cream, for the same reasons as have been 
shown in the calculations of overrun from milk of dif- 
ferent fat contents. If similar calculations are made 
for cream of different richness as those given above for 
milk, the fat available for butter-making and the yield 
of butter per 100 pounds of fat in the cream will be 
as shown below. A mechanical loss in the process 
of butter-making amounting to 2 per cent, has been 
assumed in these calculations: 



100 lbs. fat in 
cream 


Available fat 


Butter of 83 
per ct. fat 


Overrun 


Per cent 
20 
30 
40 


Ll)s. 
96.8 
97.3 
97.6 


Lbs. 
116.6 
117.2 
117.6 


Per cent 
16.6 
17.2 
17.6 



We note that the overrun for cream of different qual- 
ity under the conditions given ranges from 16.6 for 20- 
per cent, cream to 17.6 for 40-per cent, cream. A some- 
what larger overrun would be obtained when the butter 
made contains less fat and more water than assumed. 

If no losses from waste are considered in the account, 
the figures for fat available for butter will be 98.8, 99.3, 



Calculation of Butter- and Cheese Yield. 195 

and 99.6 lbs., and the overruns when the butter contains 
83% fat will be 19, 19.3, and 20 per cent. These over- 
runs are higher than will be obtained under ordinary 
creamery conditions with butter containing 83.7% fat, 
because it is impossible to reduce the manufacturing 
losses in handling the cream and butter appreciably 
below 2 per cent. 

217a. Maximum overrun for butter of a legal 
water content. If we assume that the butter contains 
the maximum amount of water allowed by law, viz., 16 
per cent, (and therefore about 80 per cent, fat), the 
overrun for both milk and cream would be somewhat 
larger than already given, as shown by the following 
figures : 



Maximum overrun from milk 



Maximum overrun from cream. 



2.5% 15.5 20% 21.0 

4:o%::::::::::::::::::::l7:8 '''^^ ^i.e 

6.0% 18.9 40% 22.0 



This table shows the highest overruns that are likely 
to be obtained when the butter is to contain no more 
than the maximum amount of water allowed by law. 
Larger overruns can only be obtained by reducing the 
losses of manufacture (which will give but slightly 
higher figures) or, fraudulently, by inaccurate weigh- 
ing or testing of the milk, cream or butter. 

218. Calculation of overrun. The overrun is calcu- 
lated by subtracting the amount of butter fat contained 
in a certain quantity of milk or cream, from the amount 



196 Testing Milk and Its Products. 

of butter made from it, and finding what per cent, this 
difference is of the amount of butter fat in the milk. 

Example 1 : 8000 lbs. of milk is received at the creamery on 
a certain day; the average test of the milk is 3.8 per cent. By 
a simple multiplication we find that the milk contained 8000 X 
.038=304 lbs. of butter fat. 350 lbs. of butter was made from 
this milk, as shown by the weights of the packed tubs. The dif- 
ference between the weight of butter and butter fat is, theirefore, 

46 lbs.; 46 is i^^=15.1 per cent, of the quantity of the butter 

fat in the milk; that is, the overrun for the day considered was 
15.1 per cent. 

The formula for the overrun is as follows : 

(b- ) flOO 

f 

h and / designating the quantities of butter and butter 
fat, respectively, made from or contained in a certain 
quantity of milk. In the preceding example, the calcu- 
lation would be as follows : (g 5o-304) x loo ^15 i pgj. cQnt. 

304 ^ 

Example 2: 1000 lbs. of cream testing 25 per cent, fat con- 
tains 1000 X. 25=250 lbs. butter fat. If 304 lbs. of butter is 
made, the overrun may be calculated by subtracting the butter 
fat from the butter, 304 — 250=54 lbs., then divide this by the 

fat in the cream and multiply by TOO; or 5^|^^=21.8 per cent., 
which is the cream overrun. 

219. Conversion factor for butter fat. In tlie ninety- 
day dairy test at the World's Columbian Exposition, 
96.67 per cent, of the fat in the whole milk was recovered 
in the butter. This butter, on tlie average, contained 
82.37 per cent, butter fat; in other words, 117.3 pounds 
of butter were made from each 100 pounds of butter 
fat in the whole milk.^ The exact conversion factor 

1 When 82.37 lbs. of butter fat will make 100 lbs. of butter, how 
much butter will 90. 0)7 lbs. of butter fat make? 83.37 :96 ;17 : :100 :x. 
X=117.3, 



Calculation of Butter- and Ckee.se Yield 197 

would be 1.173. As this is an awkward number to use, 
and as 1% is so nearly the same, it was recommended 
at the time that the approximate equivalent of butter be 
computed by multiplying the amount of butter fat 
by 1%, and this figure has been generally accepted for 
computing the yield of butter from a certain amount of 
butter fat in milk. 

The figures given are the result of more than ordinary 
care in skimming, churning and testing, and probably 
represent the minimum losses of fat in the manufactur- 
ing processes. The increase of churn over test repre- 
sented by one-sixth, or 16 per cent., may therefore be 
taken as a maximum "overrun" for milk under ordi- 
nary factory conditions. 

220. Butter yield from milk of different richness, 
a. Use of butter chart. The approximate yield of but- 
ter from milk of different richness is shown in Table XI 
in the Appendix. This table is founded on ordinary 
creamery experience and will be found to come near to 
actual every-day conditions in creameries where modern 
methods are followed in the handling of the milk and 
its products. The table has been prepared in the fol- 
lowing manner: 

It is assumed that the average) loss of fat in the skim milk is 
.20 per cent., and that 85 lbs. of skim milk is obtained from each 
100 lbs. of whole milk; to this loss of fat is added that from 
the butter milk; about 10 lbs. of butter milk is obtained per 100 
lbs. of whole milk, testing on the average .30 per cent. 

If f designate the fat in 100 lbs. of milk, then the fat recov- 
ered in the butter from 100 lbs. of milk will be 



'-(^X-20+^X-30)-'-20 



198 Testing Milk and Its Products. 

There is, on the other hand, an increase in weight in the but- 
ter made, owing to the admixture of non-fatty components 
therein, principally water and salt. Butter packed and ready 
for the market will contain in the neighborhood of 84 per cent. 
of fat (214), so that the fat recovered in the butter must be in 
creased by ig«^o=:1.19. If B therefore designate the yield of but- 
ter from 100 lbs. of milk, the following formula will express the 
relation between yield and fat content, provided there are no 
other factors entering into the problem, viz.: 

B=(f— .20) 1.19 

From this value for B, should be deducted the loss due to 
wastes in the manufacturing processes, amounting to 3 per cent, 
of the total fat in the milk handled, and we therefore have: 

B=(f— .20) 1.16 

Since this table is based on a fat content of .2 per 
cent, in the skim milk, the figures for the overrun are 
slightly lower than may be obtained in creameries pro- 
vided with up-to-date cream separators. 

221. Table XI in the Appendix, founded on this 
formula, may be used to determine the number of 
pounds of butter which milk containing 3 to 5.3 per 
cent, fat will be likely to make. It presupposes good 
and careful work in separating and churning and under 
such conditions will generally show yields of butter 
varying but little from those actually obtained. It may 
be conveniently used by the butter maker or the manager 
to check up the work in the creamery; the average test 
of the milk received during a certain period is found 
by dividing the total butter fat received, by the total 
milk, and multiplying the quotient by 100; the amount 
of butter which the total milk of this average fat con- 
tent will make, according to the table, is then compared 
with the actual churn yield. 



Calculation of Butter- and Cheese Yield. 199 

Example: A creamery receives 200,000 lbs. of milk during 
a month; the milk of each patron is tested and the fat contained 
therein calculated. The sum of these amounts of fat may be 
7583 lbs; the average test of the milk is then 3.79 per cent. Ac- 
cording to Table XI, 10,000 lbs. of milk, testing 3.8, will make 
418 lbs. of butter, and 200,000 lbs., therefore, 8360 lbs. of but- 
ter. The total quantity of butter made during the month will 
net vary appreciably from this figure if the work in the cream- 
ery has beien properly done. 

222. b. Use of overrun table. The table referred to 
above gives a definite calculated butter yield for each 
grade of milk, according to average creamery condi- 
tions. As it may be found that this table will give uni- 
formly either too low or too high results, Table XII in 
the Appendix is included, by means of which the butter 
yield corresponding to overruns from 10 to 20 per cent, 
may be ascertained in a similar way as above described. 

The total yield of butter is divided by the total num- 
ber of pounds of fat delivered; the quotient will give 
the amount of butter made from one pound of fat, and 
this figure multiplied by the fat delivered by each pat- 
ron shows the pounds of butter to be credited to each 
patron. To use the table, find in the upper horizontal 
line the number corresponding nearest to the number of 
pounds of butter from one pound of fat. The vertical 
column in which this falls gives the pounds of butter 
from 100 lbs. of milk containing the per cents, of fat 
given in the outside columns (Babcbck). 

B.— Calculation of Yield of Cheese. 

223. a. From fat. The approximate yield of green 
Cheddar cheese from 100 lbs. of milk may be found by 
multiplying the per cent, of fat in the milk by 2.7 : if / 



200 Testing Milk and Its Products. 

designate the per cent, of fat in the milk, the formula 
will, therefore, be: 

Yield of cheese=2.7 f. . . . . . (I) 

The factor 2.7 will only hold good as the average of a 
large number of cases. In extensive investigations dur- 
ing three consecutive years, Van Slyke^ found that the 
number of pounds of green cheese obtained for each 
pound of fat in the milk varied from 2.51 to 3.06, the 
average figures for the three years 1892- '94, inclusive, 
being 2.73, 2.71, and 2.72 lbs., respectively. The richer 
kinds of milk will produce cheese richer in fat, and 
will yield a relatively larger quantity of cheese, pound 
for pound, than poor milk, for the reason that an in- 
crease in the fat content of milk is accompanied by an 
increase in the other cheese-producing solids of the 
milk.2 The preceding formula would not, therefore, be 
correct for small lots of either rich or poor milk, but 
only for milk of average composition, and for large 
quantities of normal factory milk. For cured cheese 
the factor will be somewhat lower, viz., about 2.6, on 
the average. 

224. b. From solids not fat and fat. If the percent- 
ages of solids not fat and of fat in the milk are known, 
the following formula by Babcock will give close results ; 

Yield of green cheese=1.58 (-A_4-.91f) _ _ (H) 

1 N. Y. experiment station (Geneva), bulletins 65 and 82. 

2 Investigations as to the relation between the quality of the milk 
and the yield of cheese have been conducted by a number of experi- 
ment stations ; the following references give the main contributions 
published on this point; N. Y. (Geneva) exp. sta., reports 10-13, inch ; 
Wis. exp. sta., reports 11 and 12, bull. 197 ; Ont. Agr. College, reports 
lS94-'96, incl. ; Minn. exp. sta., b. 19, reports 1892-'04, incl. ; Iowa exp. 
sta., bull. 21 ; Hoard's Dairyman, 1892, p. 2400. 



Calculation of Butter- and Cheese Yield. 201 

s being the per cent, of solids not fat in the milk, and / 
the per cent, of fat.^ 

The solids not fat can be readily ascertained from the 
lactometer reading and the per cent, of fat as shown in 
par. 120, by means of Table VI in the Appendix. 

Table XIII in the Appendix gives the yield of cheese 
from 100 lbs. of milk containing from 2.5 to 6.0 per 
cent, fat, the lactometer readings of which range be- 
tween 26 and 36. By means of this table cheese makers 
can calculate very closely the yields of cheese which 
certain quantities of milk will make; as it takes into 
consideration the non-fatty solids as well as the fat of 
the milk, the results obtained by the use of this formula 
will be more correct than those found by means of 
formula (I). The uncertain element in the formula lies 
in the factor 1.58, which is based on an average water 
content of 37 per cent, in the green cheese. This may, 
however, be changed to suit any particular case, e. g , 
35 per cent. ( ^,^=1.54), 40 per cent. Vo' =1-67, etc. 
The average percentages of water in green cheese found 
by Van Slyke in his investigations referred to above, 
were for the years 1892- '94, respectively, 36.41, 37.05 
and 36.70 per cent. 

225. c. From casein and fat. If the percentages of 
casein and fat in the milk are known, the yield of cheese 
may be calculated by the following formula, also pre- 
pared by Dr. Babcock: 

Yield of cheese=l.l f+2.5 casein .... (III). 

This formula will give fairly correct results, but no 
more so than formula (II) ; it is wholly empirical. 

^ For derivation of this formula, see Wisconsin experiment station, 
twelfth report, p. 105. 



202 Testing Milk and Its Products. 

Questions. 

1. What is the average composition of American creamery 
butter, and between what extremes does the composition of butter 
vary? 

2. What is the difference between the churn yield and the re- 
sults obtained by the Babcock test? 

3. What does the overrun represent? 

4. Mention several factors that cause a large overrun. 

5. Give an illustration of how the per cent, of increase of 
churn over test is found, and how the overrun is calculated. 

6. Show by an example that butter containing 80% fat can- 
not give an overrun of more than 25%. 

7. How many pounds of butter containing 80% fat can be 
made from 100 lbs. fat? 

8. Why is the overrun from cream greater than from milk? 

9. What is the overrun when 70.5 lbs. of butter are made 
from 140 lbs. of milk, testing 3.15 per cent? 

10. What is the overrun in each of the following cases V 

220 lbs. butter from 8000 lbs. milk, testing 2.3% fat. 
250 lbs. butter from 4000 lbs. milk, testing 5.8% fat. 
600 lbs. butteir from 2000 lbs. cream, testing 25.0% fat. 
480 lbs. butter from 1000 lbs. cream, testing 40.0% fat. 

11. How much butter containing (a) 80% fat, and (b) 82.5% 
fat can be made from 3250 lbs. milk, testing 4.3% fat, assum- 
ing that the skim milk is 80% of the whole milk and contains 
0,1% fat, and the butter milk, which is the cream minus the fat, 
contains 0.25% fat? What is the overrun in each case? 

12. How much butter is obtained from 5800 lbs. milk, testing 
3.7% fat, when the overrun is (a) 12.5% and (b) 16%? 

13. Two cows in full milk produce, one 17.5 lbs, of milk a day, 
containing 4.35% fat; the other, 27.3 lbs. of milk, testing 3.4%. 
If the milk of both is made into butter or cheese, how much 
butter or cheese may be expected from each one in a week? 

14. What is a fair percentage of loss of fat by waste other 
than in skim milk and butter milk under average creamery con- 
ditions in case of milk and cream? 

15. How much butter may be made from (a) 15,640 lbs. milk, 
testing 3.8% fat, and (b) 35,842 lbs, milk, testing 4,1% fat? 
(Use Table XI, Appendix.) 



CHAPTER XIII. 
CALCULATING DIVIDENDS. 

A. — Calculating Dividends at Creameries. 

226. The simplest method of calculating dividends at 
creameries is to base the calculations on the amount of 
butter fat delivered by the various patrons. Each lot 
of milk is weighed when delivered at the creamery, and 
a small quantity thereof is saved for the composite sam- 
ple, as previously explained under Composite Tests 
(180). Some creameries test these samples at the end 
of each week, and others after collecting them for ten 
days or two weeks. If the four weekly composite sam- 
ples of a patron's milk tested 3.8, 4.0, 3.9, 4.1 per cent., 
these four tests are added together, and the sum divided 
by 4; the result, 3.95 per cent., is used as the average 
test of this milk. By multiplying the total number of 
pounds of milk delivered by this patron, by his average 
test, the total weight of butter fat in pounds delivered 
to the factory during the month is obtained. This 
weight of fat is then multiplied by the price to be paid 
by the creamery per pound of butter fat; the product 
shows the amount of money due this patron for the milk 
delivered during the time samples were taken. 

227. Price per pound of butter fat. The method of 
obtaining the price to be paid for one pound of butter 
fat varies somewhat in different creameries, on account 
of the different ways of paying for the cost of manu- 



204 Testing Milk and Its Products. 

facturing the butter. The method to be followed is 
generally determined by agreement between the manu- 
facturer and the milk producers, in case of proprietary 
creameries, or among the shareholders, in co-operative 
creameries. The following methods of paying for the 
cost of manufacture are at the present time in use in 
American creameries. 

228. I. Proprietary creameries. First. — When the 
creamery is owned by some one person or company, the 
owner or owners agree to make the butter for about 3 
cents a pound; the difference between the total receipts 
of the factory and the amount due the owner is then 
divided between the different patrons, according to the 
amount of butter fat contained in the milk which they 
delivered. 

The price charged for making butter varies from 2I/2 
to 4 cents per pound; the larger the amount of milk 
received at a factory, the lower will naturally be the cost 
of manufacturing the butter.^ 

Second. — The proprietor of the creamery sometimes 
agrees to pay a certain price for 100 lbs. of milk deliv- 
ered, according to its fat content, the price of milk con- 
taining 4 per cent, of butter fat being the standard. 
This price may be changed during the different seasons 
of the year by mutual agreement. 

Third. — A creamery owner may offer to pay 1 to 2 
cents, usually li/o cents, below the average market price 
of butter, for each pound of butter fat received in the 
milk. 

^ Bull. 56, p. 26, Wisconsin exp. station; see Report 18, Iowa State 
Daii'y (V)mniissionpr, p. .S3. 



Calculating Dividends. 205 

229. II. Co-operative creameries. Where the 

creamery is owned by the patrons, one of the stock- 
holders who is elected secretary attends to the details of 
running the factory and selling the product. His ac- 
counts show the amount of money received each month 
for the butter and other products sold, and the expenses 
of running the factory during this time. The expenses 
are subtracted from the receipts, and the balance is 
divided among the patrons, each one receiving his pro- 
portionate share according to the amounts of butter fat 
delivered in each case, as shown by the total weight and 
the average test of milk delivered during this time. 

In nearly all cases, the farmers receive about eighty 
pounds of skim milk for each one hundred pounds of 
whole milk they deliver to the factory, in addition to 
the amount received for the milk, calculated according 
to one or the other of the preceding methods. 

230. Illustration of calculation of dividends. Tn order 
to illustrate the details of calculating dividends, or the amount 

to be paid each patron for the milk delivered, when 
payments are made by each of the four systems given, it will be 
assumed that a creamery receives 5000 pounds of milk daily during 
a month, and makes 6650 lbs. of butter from the 150,000 lbs. 
of milk received during this time. The average test of this milk 
may be found by multiplying the total weight of milk delivered 
by each patron by his average test, and dividing the sum of 
these products by the total weight of milk received at the cream- 
ery (in the example given, by 150,000), the quotient being mul- 
tiplied by 100. Such calculations may show that, e. g., 5700 lbs. 
of butter fat have been received in all the milk delivered by the 
different patrons; this multiplied by 100 and divided by 150,000 
gives 3.8 as the average test, or the average amount of butter 
fat in each 100 lbs. of milk received during the month. 

So fa:r the method of calculation is common for the different 
systems of payment given above; the manner of procedure now 



206 



Testing Milk and Its Products. 



differs according to the agreement made between owner and 
patrons, or among the shareholders, in case of co-operative 
creameries. 

231. I. First.— li the net returns for the 6650 lbs. of butter 
sold during the month were $1197, and the creamery is to re- 
ceive 4 cents per pound of butter as the cost of manufacture, 
etc., the amount due the creamery is 6650X.04:=$266, and the 
patrons would receive $1197 — $266:=$931. This sum, $931, is to 
be paid to the patrons for the 5700 lbs. of butter fat, which, as 
shown above, was the weight of fat contained in the 150,000 lbs. 
of milk delivered during the month. The price of one pound of 
butter fat is then easily found: $931-^5700=16l^ cents. This 
price is paid to all patrons for each pound of butter fat deliv- 
ered in their milk during the month. The monthly milk record 
of three patrons may, e. g., be as given in the following table: 



Pat on 


First 
week 


Second 
week 


Third 
week 


Fourth 
week 


Total 
Milk 


Average 


Milk 


Test 


Milk 


Test 


Milk 


Test 


Milk 


Test 


test 


No. 1 .... 
No. 2 .... 
No. 3— - 


Lhs. 

3500 

700 

2480 


% 

3.6 
3.8 
4.2 


Lhs. 

3000 

6155 

2000 


% 

3.5 
3.8 

3.8 


Lbs. 

3600 

720 

1850 


% 

3.65 
3.6 

4.0 


Lbs. 

3450 

750 

1500 


% 

3.45 
3.7 
3.6 


Lbs. 

13.550 

2,825 
7,830 


% 

3.55 
3.73 
3.90 



Multiplying each patron's total milk by his average test gives 
the number of pounds of butter fat in his milk, and this figure 
multiplied by .16% shows the money due for his milk, as given 
below: 



Patron 


Total 
milk 


Average 
test 


Butter 
fat 


Price of fat 
per lb. 


Amount 
due 


No. 1 

No. 2 

No. 3 


Lbs. 
13,550 
2,835 
7,830 


Per cent • 
3.55 
3.7 
3.9 


Lbs. 
481.0 
104.5 
305.4 


Cents 

161/3 
161/3 
161/3 


$78.56 
17.06 
48.87 



232. Second. — "When the proprietor of a creamery agrees to 
pay a certain price for 100 lbs. of 4 per cent, milk, the receipts 
for butter sold and the price per pound of butter do not enter 
into the calculation of the amount due each patron for his milk; 



Calculating Dividends. 



207 



but the weight and the test of each patron's milk are as im- 
portant as before. If it is agreed to pay 66 cents per 100 lbs. 
of 4 per cent, milk (i. e., milk containing 4 per cent, of butter 
fat), the price of one pound of butter fat will be 66^4=16 V^ 
cents, and the amount due each patron is found by multiplying 
the total weight of butter fat in his milk by this price. To 
facilitate this calculation, so-called EeJative-Value Tables have 
been constructed, the use of which is explained below (238). 

233. Third. — If a creamery agrees to pay for butter fat, say 
1% cents per pound below the average market price of butter 
each month, the price of one pound of butter fat is found by 
averaging the market quotations and subtracting 1^4 cents there- 
from. If the four weekly market prices were 17V^, 17, 16^/^ and 
19 cents, the average of these would be 17 Yo cents, and this less 
IV2 gives 16 cents as the price per pound of fat to be paid to 
the patrons; this price is then used in calculating the dividend 
as in case of first method (231). 



Patron 


Total I Average 
milk test 


Butter 
fat 


Price of fat 
per lb. 


Amount 
due 


No. 1 

No. 2 

No. 3 


Ll)s. Per cent 

13,550 3.55 

2,825 3.7 

7,830 3.9 


Lbs. 
481.0 
104.5 
305.4 


Cents 
16 
16 
16 


$76.96 
16.72 

48.86 



234. II. If the creamery is owned by the farmers, the run- 
ning expenses for a month are subtracted from the gross returns 
received for the butter, and the price to be paid per pound of 
butter fat is found by dividing the amount left by the total 
number of pounds of butter fat delivered during the month. 
This price is used for paying each patron for his milk according 
to the amount of fat contained therein, as already explained un- 
der Proprietary Creameries (231). 

The monthly running expenses of a co-operative creamery gen- 
erally include such items as the wages of the butter maker (and 
manager or secretary, if these officers are salaried), labor (haul- 
ing, helper, etc.), cost of butter packages, coal or wood, salt 
and other supplies, freight and commission on the butter sold, 
repairs and insurance on buildings, etc. A certain amount is 
also paid into a sinking fund (say, 5 cents per 100 lbs. of milk), 



208 Testing Milk and Its Products. 

which represents the depreciation of the property, wear and tear 
of building and machinery, bad debts, etc. Thesei items are 
added together, and their sum subtracted from the gross receipts 
for the butter sold during the month, 

235. Assuming the receipts for the butter during the month 
to be $1197, and the running expenses of the factory $285, the 
amount to be divided among the patrons is $912; the quantity 
of butter fat received was 5700 lbs., and the price per pound of 
butter fat will therefore be 16 cents. The account will then 
stand as given in (233). 

236. Other systems of payment. Besides these four 
systems of payment, there are various other agreements 
made between manufacturer and producer, but with 
them all the one important computation is the price to 
be paid per pound of butter fat; this forms the basis of 
calculating the factory dividends, when milk is paid for 
by the Babcock test. 

237. Paying for butter delivered. In some instances 
patrons desire to receive pay for the quantity of butter 
which the milk or cream delivered by them would make. 
This can be ascertained quite satisfactorily from the total 
receipts and the total weights of both butter fat and but- 
ter. The total money to be paid for butter (the net re- 
ceipts) are divided by the number of pounds of butter 
sold, to get the price to be paid per pound of butter ; the 
total yield of butter divided by the total amount of 
butter fat delivered in the milk, gives the amount of 
butter corresponding to one pound of butter fat, and 
the number of pounds of fat delivered by each patron 
is then multiplied by this figure. This method requires 
more figuring than those given in the preceding, and the 
dividends are no more accurate, in fact less so, than 
when calculations are based on the price per pound of 
fat. 



Calculating Dividends. 209 

237a. Making butter ''for the overrun." When 
cream is bought on the basis of paying the market price 
of butter for each pound of butter fat in the cream, the 
margin received by the cream buyer, if he makes this 
cream into butter, is influenced both by the price of 
butter and the per cent, of overrun he obtains. If the 
price of butter is 20c. and the overrun is 20%, each 
pound of butter fat makes 1.2 lbs. of butter, and the 
buyer receives 24 cents for the butter, or 4 cents margin 
on the 1.2 lbs. of butter made, which is equal to 3% 
cents per pound of butter. If the price of butter is 
36 cents, and the overrun 20%, the cream buyer receives 
1.2X36=43 cents for the butter, or 7 cents for 1.2 lbs. 
of butter, equivalent to 5.8 c. per pound of butter. 

238. Relative-value tables. These tables give many 
of the multiplications used in computing the amount 
due for various weights of milk of different fat con- 
tents. They can easily be constructed by any one 
as soon as the price of one pound of fat is determined 
in each case. If the price to be paid per pound of fat 
is, say 25 cents, the value of each 100 lbs. of milk of 
different quality is found by multiplying its test by 25. 
If the average tests of the different patrons* milk vary 
from 3 to 5 per cent., the relative-value table would be 
as follows. 

3.0X25=75c. per 100 lbs. , 3.6X25=90c. per 100 lbs. 



3.1X25=77.50. 

3.2X25=80c. 

3.3X25=82.5c. 

3.4X25=85.0c. 

3.5X25=87.5c. 



3.7X25=92 5c. 
3.8X25=95.0c. 
3.9X25=97.5c. 
4 0X25=100c. 
etc. 



By continuing this multiplication, or adding the mul- 
tiplier each time for each tenth of a per cent, up to 5 

H 



210 



Testing Milk and Its Products. 



per cent, of fat, a table is made that can be used for 
calculating the amount due per 100 lbs. of milk at the 
price per pound given, and the weight of milk delivered 
by each patron is multiplied by the price per 100 lbs. of 
milk shown in the table opposite the figure representing 
his test. 

Example: A patron supplies 2470 lbs. of milk, testing 3.2 
per cent, of fat; price per pound of fat, 25 cents; he should 
then receive 24.70 X.80=$19. 76 (see above table). Another pat- 
ron delivering 3850 lbs. of milk testing 3.8 per cent, vpill re- 
ceive, at the same price per pound of fat, 38.50X.95=:$35.57. 

The relative-value tables in the Appendix give the 
price per 100 lbs. of milk testing between 3 and 6 per 
cent, fat, when the price of three per cent, milk varies 
from 30 to 90c. per 100 lbs. In using the tables, first 
find the figure showing the price which it has been de- 
termined to pay for 100 lbs. of milk of a certain qual- 
ity, say 3 or 4 per cent.-milk; the figures in the same 
vertical column then give the price to be paid per 100 
lbs. of milk testing between 3 and 6 per cent. 

Example 1: It has been decided to pay 90 cents per 100 lbs. 
of 4 per cent.-milk. The figure 90 is then sought in the table in 
the same line as 4.0 per cent., and the vertical column in which 
it is found gives the price per 100 lbs. of 3 to 6 per cent.-milk ; 
3.8 per cent.-milk is thus worth 85 cents per 100 lbs. and 4.5 per 
cent.-milk, $1.01, under the conditions given. The prices of milk 
of other qualities are found in the same way. 

Example 2: In the example referred to under Illustrations of 
calculating creamery dividends (I b, 231), the figures for the 
patrons Nos. 1, 2 and 3, would be as follows: 



Patron 


Milk delivered 


Averajje 
test 


Price per 100 lbs. 
of milk 


Amount 
due 


No. 1 

No. 2 . 

No. 3 


Lbs. 
13,550 
2,825 
7,830 


Per cent 
3.55 
3.7 
3.9 


Cents 
58.5 
61.0 
64.0 


$79.26 
17.23 
50.11 



Calculating Dividends. 211 

239. Milk- and cream dividends. When cream from 
farm hand separators or other sources is brought to a 
factory receiving and skimming whole milk, the cream 
patron's dividend should be calculated a little differ- 
ently than that of the milk patron (210). 

In one case the dividend is based on the weight and 
the test of cream and in the other on the weight and 
the test of milk; the difference between the two being 
represented by the fat left in the factory skim milk. 
This skim milk fat is included in the milk patron's 
dividend and consequently ought also to be allowed for 
in calculating the amount due the cream patron. Such 
an allowance can be fairly made by multiplying the 
cream fat by 1.03. The amounts of fat thus obtained 
represent very nearly the fat in the milk from which 
the cream was skimmed and assumes that the fat re- 
turned to the milk patron in his skim milk is about 
three per cent, of the total fat in his whole milk. 

Since both milk and cream patron suffer the same 
manufacturing losses in the butter milk, an equaliza- 
tion of the skimming losses is all that is necessary in 
order to put both on a uniform basis for calculating 
dividends. 

240. The following illustration will help to make these cal- 
culations clearer. Milk patron No. 1 delivers to the creamery 
during the month 5320 lbs. of milk testing 3.8 per cent, fat, 

which therefore contains p-^Q^3.8 \ _202 lbs. butter fat. If the 

V 1(H) y 
price paid the patrons is 20c., then 202 multiplied by 20 amounts to 
$40.40, the money due this patron for his milk. If another pat- 
ron sent 485 lbs. of cream testing 22.0 per cent, fat to the same 
factory during the month, the weight of fat in the cream is first 
found in the same way as in the milk. (i§^A22^=io6.7 lbs. but- 



212 Testing Milk and Its Products. 

ter fat. Now, instead of multiplying this butter fat by 20c., as 
was done for the whole milk patron, it must first be multiplied 
by 1.03. 106.7X1.03=109.9 lbs. butter fat which is now multi- 
plied by 20c. per pound, giving $21.98. This is the amount due 
the cream patron when both milk and cream are received at the 
same factory and the cream from both patrons is churned to- 
gether.^ 

241, The amount of cheese made from a certain quan- 
tity of milk depends, as before shown, in a large meas- 
ure on the richness of the milk in butter fat (223). 
[Rich milk will give more cheese per hundred weight 
than poor milk, and within the ordinary limits of nor- 
mal factory milk the increased yields will be nearly, but 
not entirely, proportional to the fat contents of the dif- 
ferent kinds of milk. Since the quality of the cheese 
produced from rich milk is better than that of cheese 
made from thin milk and will demand a higher price, 
it follows that no injustice is done by rating the value 
of milk for cheese production by its fat content. This 
subject was discussed frequently during the nineties in 
experiment station publications and in the dairy press 
(223). Among others, Babcock has shown that the price 
of cheese stands in a direct relation to its fat content.^ 
Prof. Kobertson, ex-Commissioner of Agriculture of Can- 
ada, is authority for -the statement that the quality of 
the cheese made from milk containing 3.0 to 4,0 per 
cent, of fat was increased in value by one-eighth of a 
cent per pound for every two-tenths of a per cent, of 
fat in the milk,^ a figure which is fully corroborated by 

117th report Wis. exp. station, p. 90 ; 20th report, pp. 130-131. 

2 Wisconsin exp. station, 11th report, p. 134. 

3 Hoard's Dairyman, March 29, 1895. 



Calculating Dividends. 213 

Dr. Babcock's results. The injustice of the ''pooling 
system," by which all kinds of milk receive the same 
price, is evident from the preceding; if the milk of a 
certain patron is richer than that of others, it will make 
a higher grade of cheese, and more of it per hundred- 
weight; hence a higher price should be paid for it. 

Payment on the basis of the fat content of milk is, 
therefore, the most equitable method of valuing milk 
for cheese making, and in case of patrons of cheese fac- 
tories as with creamery patrons, dividends should be 
calculated on the basis of the results obtained by test- 
ing the milk delivered. The testing may be conven- 
iently arranged by the method of composite sampling, 
in the way already described for creameries (180). 

242. Cheese factory dividends, (a) Divide^ids 
based on fat test alone. As in the case, of creameries, 
the price to be paid per pound of butter fat must first 
be ascertained. The factory records should show the 
number of pounds of cheese made from the total milk 
delivered to the factory during a certain time, generally 
one month, and the money received for this cheese. The 
cost of making the cheese and all other expenses that 
should be paid for out of the money received for the 
cheese, are deducted from the total receipts, and the 
difference is divided among the patrons in proportion 
to the amounts of butter fat delivered in the milk. 

The weights of the milk delivered and the tests of the 
composite samples furnish data for calculating the 
quantities of butter fat to be credited to each patron. 



214 Testing Milk and Its Products. 

The money to be paid to the patrons is then divided by 
the total weight of butter fat delivered to the factory 
and the price of one pound of fat thus obtained. The 
money due each patron is now found by multiplying 
the total number of pounds of butter fat in his milk by 
this price per pound. 

(b) Dividends based on fat and solids-not-fat (lacto- 
meter readings). A close estimate of the cheese value 
of each patron's milk may be made, as explained in 
par. 224, b., by the use of table XIII in the Appendix. 
When the cheese yield of each patron's milk is found by 
this method, the money to be distributed among the 
patrons is divided by the sum of the figures found 
by these two tests, instead of by the total butter fat. The 
figure thus obtained is the price to be paid each patron 
per pound cheese that may be made from his milk as 
shown by both the fat test and the lactometer reading. 

(c) Dividends based on "the fat plus tivo metiwd. ' 
The money due patrons for milk delivered at cheese 
factories may be calculated by adding two to the per 
cent, of fat in the milk, and otherwise . proceeding as 
explained above under par. 242a. This is the method 
advocated by Prof. H. H. Dean of Guelph (Ont.) Ag- 
ricultural college.^ It has been adopted at many Cana- 
dian cheese factories and at some factories in this coun- 
try. 

(d) Dividends based on the fat and casein tests. The 
results obtained by the fat test and the Hart casein 

1 Bull. 114, Ont. Agr. College; see also Dean, Canadian Dairying, p. 
146. 



Calculating Dividends. 215 

test (258) are added together; the pounds of milk de- 
livered by each patron are multiplied by this ligure 
and the product multiplied by the price to be paid foi 
the sum of the fat and the casein.^ This price per 
pound is obtained in the same way as the price per 
pound of fat. Each patron's milk is multiplied by the 
sum of the fat and the casein tests and the money to 
be distributed to the patrons is divided by the sum of 
these figures obtained for all patrons for the period 
covered. 

The illustrations already given for calculating patrons' 
dividends at creameries according to the various meth- 
ods will serve equally well to show the manner in which 
dividends are calculated at a cheese factory. For the 
sake of clearness an example is given that applies di- 
rectly to cheese factories. 

243. Illustration of calculation dividends. It may be 

assumed that 15,000 libs, of green cheese is made from 150,000 
lbs. of milk delivered to a factory in a month. According to the 
weighings and the tests made, the milk contained 5,700 lbs. of 
butter fat. If the cheese sold at an average price of 7y2 cents 
a pound, the gross receipts would be $1,125.00. The amount to 
be deducted from the gross receipts will depend on the agree- 
ment made between the factory operator and the patrons, in 
case of proprietary cheese factories, or between the shareholders 
and the maker, when the factory is run on the co operative plan. 
As before we shall consider these systems separately. 

244. I. Proprietary cheese factories. The owner of the 
factory generally agrees to make the cheese for a certain price 
per pound and to pay the patrons what is left after deducting 
this amount. If the price agreed on is 1^ cents per pound of 
green cheese, this would amount to $225 in the example given. 
Subtracting this sum from the gross receipts, $1,125, leaves $900, 

1 Wisconsin expt. station, bull. 197. 



216 



Testviig MUk and Its Products 



which is to be paid the patrons. The total amount of butter fat 
delivered by the patrons was 5,700 lbs.; hence the price of one 
pound of butter fat will be 900-r-5,700=.1577, or* 15.8 cents. 
Taking the figures for the three patrons already mentioned un- 
der Creamery Dividends, we then have: 



Patron 


Total milk 


Average 
test 


Butter fat 


Price per 
lb. of fat 


Amount 
due 


No. 1_— 
No. 2___. 
No. 3___. 


Lbs. 
1^,550 
2,825 
7,830. 


Per cent 
3.55 
3.7 
3.9 


Lbs. 
481.0 
104.5 
305.4 


Cents 
15.8 
15.8 
15.8 


$76.00 
16.51 
48.25 



245. II. Co-operative cheese factories. The method of pay- 
ment at co-operative cheese factories is nearly the same as that 
already given, except that a certain sum representing the ex- 
penses is subtracted from the gross receipts for the cheese, and 
the balance is divided among the patrons according to the amount 
of butter fat furnished by each, in the same manner as in the 
above case, after the price of a pound of fat has been obtained. 

The price per 100 lbs. of milk can be calculated in the same 
way as at creameries, by multiplying the test of each lot by the 
price per pound of fat.* 



Questions. 

1. How much money is due each of three patrons of a cream- 
ery when the following weights of milk are delivered by each: 
A — 5750 lb. milk, composite tests, 4.0 — 4.8 — 4.2 per cent. 
B — 955 lb. milk, composite tests, 4.6 — 5.0 — 4.8 per cent. 
C — 10,538 lb. milk, composite tests, 3.2 — 3.5 — 3.0 per cent. 

(a) When 700 lbs. of butter axe sold for $200, and the cost of 
making is 3i^c. per lb; 

(b) When the factory agrees to pay $1.00 per 100 lbs. milk, 
testing 4% fat; 



1 Suggestions regarding the organization of co-operative creameries 
and cheese factories will be found in the Appendix, following Table 
XV. Draft of constitution and by-laws for co-operative factory as- 
sociations are also given in the Appendix. It is hoped that these will 
prove helpful to farmers who contemplate forming such associations. 



CHAPTER XIV. 

CHEMICAL ANALYSIS OF MILK AND ITS 
PRODUCTS. 

246. An outline of the methods followed in determin- 
ing quantitatively the main components of milk and its 
products is given in the following for the guidance of 
advanced dairy students. This work cannot be done 
outside of a fairly well-equipped chemical laboratory, 
or by persons who have not been accustomed to handling 
delicate chemical apparatus and glassware, analytical 
balances, etc., and who have not a knowledge of, at 
least, the elements of chemistry and chemical reactions. 

A.— Milk. 

247. In a complete milk analysis, the specific gravity 
of the milk is determined, and the following milk com- 
ponents: water, fat, casein and albumen, milk sugar, 
and ash. The methods of analysis described in the fol- 
lowing are those adopted by the Association of Official 
Agricultural Chemists of North America, which, with 
but slight modifications, are in general use in the chemi- 
cal laboratories of all American experiment stations and 
agricultural colleges.^ 

248. a. Specific gravity is determined by means of 
a picnometer or specific-gravity bottle, since more ac- 

1 The complete methods of analysis adopted by the Associatio-n of 
Official Agricultural Chemists are published by the Bur. of Chemistry 
of the U. S. Department of Agriculture ; see Bull. No. 107, pp. 117-128. 



218 Testing Milk and Its Products. 

curate results will thus be reached than by using an or- 
dinary Quevenne lactometer. A thermometer is ground 
into the neck of the specific-gravity bottle so as to form 
a stopper, and the bottle is provided with a glass-stop- 
pered side-tube, to furnish an exit for the liquid on ex- 
panding. A specific-gravity bottle holding 100 grams 
of water is preferably used. The empty and scrupu- 
lously cleaned bottle is first weighed on a chemical bal- 
ance. The bottle is then filled with recently-boiled dis- 
tilled water of a temperature below 60° F. (15.5° C.) ; 
the thermometer is inserted, and the bottle is warmed 
slightly by immersing it for a moment in tepid water 
and left standing until the thermometer shows 60° F. ; 
the opening of the side tube is then wiped off and closed 
with the stopper, and the water on the outside of the 
bottle and in the groove between its neck and the ther- 
mometer is wiped off with filter paper or a clean hand- 
kerchief, when the bottle is again weighed. The weight 
being recorded, the bottle is emptied and dried in a 
water oven, or if sufficient milk is at hand, the bottle is 
repeatedly rinsed with the milk, the specific gravity of 
which is to be determined. It is then filled with milt 
in a similar manner as in case of water; the tempera- 
ture of the milk should be slightly below 60° F. and is 
slowly brought up to this degree after the bottle has 
been filled, proceeding in the same way as before with 
water; the weight of the bottle and milk is then taken. 
The weights of water and of milk contained in the 
specific-gravity bottle are found by subtracting the 
weight of the empty bottle from the second and the 
third weights, respectively, and the specific gravity o^' 



Chemical Analysis of Milk and Its Products. 219 

the milk then found by dividing the weight of the milk 
by that of the water. 

Example: Weight of sp. gr. bottle+water. , .146.9113 grams. 
Weight of sp. gr. bottle empty. . . 46.9423 grams. 

Weight of water 99.9690 grams. 

Weight of sp. gr. bottle+milk 149.8708 grams. 

Weight of sp. gr. bottle empty. . . 46.9423 grams. 

Weight of milk 102.9285 grams. 

Sp. gr. of milk=^*^'— 1.0296. 

249. If a plain picnometer without a thermometer attached 
is available, the method of procedure is similar to that described, 
with the difference that the temperature of the water and of the 
milk must be brought to 60° F. before the picnometer is filled, 
or the picnome4;er filled with either liquid is placed in water in a 
small beaker, which is very slowly warmed to 60° F. and kept at 
this temperature for some time so as to allow the liquid in the 
picnometer to reach the temperature desired; th temperature of 
the water in the beaker is ascertained by means of an accurate 
chemical thermometer. The perforated stopper is then wiped off, 
the picnometer is taken out of the water, wiped and weighed. It 
is necessary to weigh very quickly if the room temperature is 
much above 60" F.. as in such cases the expanding liquid will 
flow on to the balance pan, with a resultant loss in weight from 
evaporation. 

The weights of specific-gravity bottle or picnometer, empty 
and filled with water, need only be determined a couple of times, 
and the averages of these weighings are used in subsequent de- 
terminations. 

250. Westphal balance. Where only a small amount 
of milk is available, or in rapid work, the specific grav- 
ity may be taken with considerable accuracy by means 
of a Westphal balance. The arrangement and use of 
this convenient little apparatus is readily explained 
verbally. 



220 Testing Milk and Its Products. 

For the determination of the specific gravity of lop- 
pered milk, see 263. 

251. b. Water. The milk is weighed into a perfor- 
ated copper tube filled with prepared dry asbestos. The 
tubes are made from perforated sheet copper, with holes 
about .7 mm. in diameter and about .7 mm. apart; they 
are 60 mm. long, 25 mm. in diameter and closed at the 
bottom. The asbestos is prepared from clean fibrous 
asbestos, which is ignited at low heat in a muffle oven, 
treated with a little dilute HCl (1:3) and then with 
distilled water till all acid is washed out; it is then 
torn in loose layers and dried at a low temperature in 
an air bath ; when dry it can be easily shredded in fine 
strings, and is placed in a w^ide-mouth, glass-stoppered 
bottle. 

About two grams of asbestos are placed in each tube, 
packing it rather loosely; the t ibe is then weighed, a 
small narrow beaker being inverted over it on the scale 
pan. 5 cc. of milk are now dro])ped on to the asbestos 
from a 5 cc. fixed pipette, the b« aker again placed over 
the tube, and the weight of the 5 cc. of milk delivered 
+copper tube taken. The wei^^ht of the milk is ob- 
tained by difference. The tubes are then placed in a 
steam oven and heated at 100° 0. until they no longer 
decrease in weight, which will ordinarily take about 
three hours. Place in a desiccator until cold, and weigh ; 
the difference between the weight of the tube-|-milk and 
this last weight gives the water contained in the milk, 
which is then calculated in per cent, of the quantity of 
milk weighed out. 



Chemical Analysis of Milk and Its Products. 221 

Example: Weight of tube+beaker+milk. . . . 29.3004 grams. 
Weight of tube+beaker 24.1772 grams. 

Milk weighed out 5.1232 grams. 

Weight of tube+beaker+milk 29.3004 grams. 

Weight of tube+beaker+milk,dry 24.9257 grams. 

Weight of water 4.3747 grams. 

Per cent, of Avater in milk=^-^^?^^-4^=85.39 per cent. 

5.1232 

Note. The per cent, of total solids in milk is often 
given, instead of that of water; this may be readily ob- 
tained by subtracting the weight of the empty tnbe 
from that of the tube filled with milk solids, and finding 
the per cent, of the milk weighed out which this differ- 
ence makes. In the above example, the weight of milk 
solids thus is 24.9257— 24.1772=.7485 gram, and the 
per cent, of total solids in the milk=14.61 per cent. 

252. Alternate method. Five oc. of milk" are measured out 
on a weighed flat porcelain dish (50-60 mm. in diameter; porce- 
lain covers will answer the purpose well if the handle be broken 
off or ground off level on an emery wheel) ; this is weighed rap- 
idly; two or three drops of 30 per cent.-acetic acid are added, 
and the dish is dried in a steam oven at 100" C. until no further 
loss in weight occurs. After cooling in a desiccator, the weight 
of the milk solids is obtained, and by calculation as before, the 
per cent, of water or total solids in the milk. 

253. c. Fat. The dried tubes from the water deter- 
mination are placed in Caldwell extractors and con- 
nected with weighed, numbered glass flasl^ (capacity, 
2-3 oz.) ; the extractors are attached to upright Liebig 
condensers and the tubes extracted with pure ether, 
free from water, alcohol or acid, until all fat is dis- 
solved; 4-5 hours' extraction is sufficient for whole 
milk; in case of samples of skim milk it is well to con- 



222 Testing Milk and Its Products. 

tinue the extraction for 8 hours. The ether is then re- 
covered by distillation, and the flasks dried in a steam 
oven until constant weight; after cooling they are 
weighed and the amount of fat contained in the quan- 
tity of milk originally weighed into the tubes is thus 
ascertained, and the per cent, present ;n the milk cal- 
culated. > 

Example: Weight of flask -f fat 15.8039 grams. 

Weight of flask 15.5171 grams. 

Weight of fat 2868 gram. 

Milk weighed out 5.1232 grams. 

Per cent, of fat in milk= -^*^^^^^^ — 5.60 per cent. 

254. The Gottlieb method for the determination 
of fat.^ 10 cc. of milk are measured into a glass cyl- 
inder, % inch in diameter and about 14 inches long (a 
100 cc. burette or a Eudiometer tube will do) ; 1 cc. 
cone, ammonia is added and mixed thoroughly with the 
milk; the following chemicals are next added in the 
order given : 10 cc. of 92 per cent, alcohol, 25 cc. of 
washed ether, and 25 cc. petroleum ether (boiling pt., 
below 80° C), the cylinder being closed with a moist- 
ened cork stopper and the contents shaken several times 
after the addition of each chemical. The cylinder is then 
left standing for six hours or more. The clear fat solution 
is next pipetted off into a small weighed flask, by means 
of a siphon drawn to a fine point (see fig. 6, loc. cit), 
which is lowered into the fat solution to within i/o cm. 
of the turbid bottom layer. After evaporating the ether 
solution in a hood, the flasks are dried in a steam oven 

iLandw. Vers. Sta., 40 (1892'), pp. 1-27. The method is also spoken of 
as the Rose-Gottlieb method. 



Chemical Analysis of Milk and Its Products. 223 

for two to three hours, and weighed. This method is 
applicable to new milk, skim milk, butter milk, whey, 
cream, cheese, condensed milk and milk powder, but has 
been found of special value for determining fat in skim 
milk, butter milk, cheese, and condensed milk. In the 
case of products high in fat, a second treatment with 
10 cc. each of ether and petroleum is advisable in order 
to recover the last traces of fat. 

255. d. Casein and albumen. The sum of these com- 
ponents is generally determined by the Kjeldahl 
method.^ 5 cc. of milk are measured carefully into a 
800 cc. Jena flask, 20 cc. of concentrated sul- 
furic acid (C. P.; sp. gr., 1.84) are added, and .7 gram 
of mercuric oxid (or its equivalent in metallic mer- 
cury) ; the mixture is then heated over direct flame 
until it is straw-colored or perfectly white; a few crys- 
tals of potassium permanganate are now added till the 
color of the liquid remains green. All the nitrogen in 
the milk has then been converted into the form of am- 
monium sulfate. After cooling, 200 cc. of ammonia- 
free distilled water are added, 20 cc. of a solution of 
potassium sulfid (containing 40 grams sulfid per liter), 
and a fraction of a gram of powdered zinc. A quan- 
tity of semi-normal HCl-solution, more than sufficient 
to neutralize the ammonia obtained in the oxidation of 
the nitrogen in the milk^ is now carefully measured out 
from a delicate burette (divided into -oV cc.) into a re- 
ceiving flask and the flask connected with a distillation 
apparatus. At the other end, the Jena flask containing 

I Frescnius' Zeitschrift, 22, p. 366 ; U. S. Dept. Agr., Bur. of Chem., 
Bull. 107, p. 5. 



224 Testing Milk and Its Products. 

the watery solution of ammonia sulfate is connected, 
after adding 50 cc. of a concentrated soda solution (1 
pound "pure potash" dissolved in 500 cc. of distilled 
water and allowed to settle) ; the contents of the Jena 
flasks are now mixed and heated to boiling, and the 
distillation is continued for forty minutes to an hour, 
until all ammonia has been distilled over. 

The excess of acid in the Erlenmeyer receiving-flask 
is then accurately titrated back by means of a tenth- 
normal standard ammonia-solution, using a cochineal- 
solution^ as an indicator. From the amount of acid 
used, the per cent, of nitrogen is obtained ; and from it, 
the per cent, of casein and albumen in the milk by mul- 
tiplying by 6.25.^ The amount of nitrogen contained in 
the chemicals used is determined by blank experiments 
and deducted from the nitrogen obtained as described. 

Example: The weight of 5 cc. of milk (as obtained in deter- 
mining the water in the milk) was 5.1465 grams. 5 cc. of stand 
ard HCl are added to the receiver, and 1.55 cc. of -^r^ alkali 
solution are used in titrating back the excess of acid. 1.55 cc. 
of -^ alkali = ^-^=.31 cc. -^ acid solution; the ammonia dis- 
tilled over therefore neutralized 5.00 — .31=4.69 cc. acid. By 
blank trials it was found that the reagents used furnished an 
equivalent of .02 cc. acid in the distillate; this quantity sub- 
tracted from the acid-equivalent of the nitrogen of the milk 
leaves 4.67 cc. 1 cc. semi-normal HCl-solution corresponds to 
7 milligrams or .007 gram of nitrogen; 4.67 cc. ~- HCl therefore 
represents .03269 gram of nitrogen. This quantity of nitrogen 
was obtained from the 5.1465 grams of milk measured out; the 

milk therefore contains ^ -^"" =.635 per cent, of nitrogen, and 

5.1465 ^ ^ ' 

.635X6.25:=::3.97 per cent, of casein and albumen. 

^ Sutton, Volumetric Analysis, 4th edition, p. 31. 
' The factor 6.30 or 6.37 is more correct for the albuminoids of milk, 
but has not yet been generally adopted (p. 15, foot note)." 



Chemical Analysis of Milk and Its Products , 225 

256. Casein and albumen may be determined sepa- 
rately l)y A^an Slyke's method-/ 10 grams of milk are 
weighed out and diluted with about 90 cc. of water at 
40°-42° C. 1.5 cc. of a 10 per cent, acetic-acid solution 
are then added ; the mixture is well stirred with a glass 
rod and the precipitate allowed to settle for 3 to 5 min- 
utes. The whey is decanted through a filter and the 
precipitate washed two or three times with cold water. 
The nitrogen is determined in the filter paper and its 
contents by the Kjeldahl method; blank determinations 
with the regular quantities of chemicals and the filter 
paper used are made, and the nitrogen found therein 
deducted. The per cent, of nitrogen obtained multi- 
plied by 6.25 gives the per cent, of casein in the milk. 

257. Albumen is determined in the filtrate from the 
casein-precipitate ; the filtrate is placed on a water bath 
and heated to boiling for a period of from ten to 
fifteen minutes. The washed precipitate is then treated 
by the Kjeldahl method for the determination of nitro- 
gen; the amount of nitrogen multiplied by 6.25 gives 
the amount of albumen in the milk. The difference be- 
tween the total nitrogenous components found by the 
Kjeldahl method, and the sum of the casein and the 
albumen, as given above, is due to the presence in milk 
of a third class of nitrogen compounds (18).- 

257a. The protein of milk may also be obtained by 
calculation from the total solids of the milk by the use 
of the following formula worked out by Mr. Geo. A. 



1 Bulletin 107, p. 117, Bur. of Chem., U. S. Dept. of Agriculture. 

2VolnmeTric detorminntions of casein in milk have been proposed 
by Van Slyke and Bosworth (Geneva, N. Y.) expt. station, tech.. bull. 
10) and by Hart (Wis. expt. station, research bull. 11). 
15 



226 Testing Milk and Its Products. 

Olson^: P=T— _T_ The results obtained by this 

1.34 "^ 

formula are quite satisfactory. If we assume that .8 
of the milk protein is casein, this component can also be 
obtained from the solids of the milk by a simple calcula- 
tion by the use of the preceding formula. 

258. Hart's test for casein in milk. The following 
test for casein in milk has been published by the "Wis- 
consin experiment station.- 

Two cc. of chloroform, 20 cc. of a .25 per cent, solu- 
tion of acetic acid, and 5 cc. of milk (both these latter 
of a temperature of about 70° F.) are measured into 
small tubes of special construction holding about 35 cc, 
the lower ends of which are narrow and graduated to 
.1 cc. The mixture is shaken for 10 to 20 seconds and 
the tubes then whirled 7% or 8 minutes in a centri- 
fuge of 15 inches diameter, making 2000 revolutions per 
minute. (The use of a metronome is recommended to 
facilitate the control of the speed.) After whirling, 
the tubes are taken out of the centrifuge and allowed 
to stand for 10 minutes, and the percentage of casein 
read off directly from the scale on the lower end of the 
tubes, each division of which represents .2 per cent, of 
casein when 5 cc. of milk are measured out. The test 
calls for considerable nicety of manipulation, but ap- 
pears to give reliable results when the directions given 
are strictly followed.* 

259. e. Milk sugar is generally determined by differ- 
ence, the sum of fat, casein and albumen (total NX6.25), 

1 Journ. Ind. and Eng. Chemistry, I, 1909, p. 253. 

' Report 24, p. 117 : "A simple method for the estimation of casein 
in cow's mlllj." 

' See also Clrc. 10. Wis. expt. sta., Operating the casein test at cheese 
factories. 



Chemical Analysis of Milk and Its Products. 227 

and ash, being subtracted from the total solids. It may- 
be determined directly by means of a polariscope, or 
gravimetrically by Fehling's solution; only the former 
method, as worked out by AViley/ will be given here. 

The specific gravity of the milk is accurately deter- 
mined, and the following quantities of milk are meas- 
ured out by means of a 100 cc. pipette graduated to .2 
cc. (or a 64 cc. pipette made especially for this purpose, 
with marks on the stem between 63.7 and 64.3 cc), ac- 
cording to the specific gravities given : 1.026, 64.3 cc. ; 
1.028, 64.15 cc; 1.030, 64.0 cc ; 1.032, 63.9 cc ; 1.034, 
63.8 cc ; 1.036, 63.7 cc These quantities refer to the 
Schmidt-Haensch half-shadow polariscopes, standard- 
ized for a normal weight of 26.048 grams of sugar. The 
milk is measured into a small flask graduated at 100 cc. 
and 102.6 cc; 30 cc of mercuric-iodid solution (pre- 
pared from 33.2 grams potassium iodid, 13.5 grams mer- 
curic chlorid, 20 cc. glacial acetic acid and 640 cc 
water) are added; the flask is filled to 102.6 cc. mark 
with distilled water, the contents mixed, filtered through 
a dry filter, and when the filtrate is perfectly clear, the 
solution is polarized in a 200 millimeter tube. The 
reading of the scale divided by 2, shows the per cent, 
of lactose (milk sugar) in the milk. Take five readings 
of two different portions of the filtrate, and average 
the results. 

260. f. Ash. About 20 cc. of milk are measured into 
a flat-bottom porcelain dish and weighed ; about one-half 
of a cc. of 30 per cent.-acetic acid is added,, and the 
milk first dried on water bath and then io^nited in a 



* Agricultural Analysis. TTI, p. 275 ; Am. Chem. Jour., 6, p. 289 et seq. 



228 Testing Milk and Its Products. 

muffle oven at a low red heat. Direct heat should not 
be applied in determining the ash in milk, since alkali 
chlorids are likely to be lost at the temperature to which 
milk solids have to be heated to ignite all organic carbon. 

Example: Weight of porcelain dish+milk... . 49.0907 grams. 
Weight of porcelain dish 28.3538 grams. 

Weight of milk 20.7369 grams. 

Weight of dish+milk, after ignition 28.5037 grams. 
Weight of dish 28.3538 grams. 

Weight of milk ash .1499 gram 

Per cent, of ash=4^'?;^=.72 per cent. 
20.7369 ^ 

The residue from the determination of solids by the 
Alternate Method given (252) may also be used for the 
ash determination. 

B.— Cream, Skim milk, Butter milk, Whey, Con- 
densed MILK. 

262. The analysis of these products is conducted in 
the same manner as in case of whole milk, and the same 
constituents are determined, when a complete analysis 
is wanted. Skim milk, butter milk, and whey con- 
tain relatively small quantities of solids, and espe- 
cially of fat, and it is, therefore, well to weigh out a 
larger quantity than in case of whole milk ; if possible, 
toward 10 grams. The acidity of sour milk and butter 
milk must be neutralized with sodium carbonate pre- 
vious to the drying and extraction, as lactic acid is solu- 
ble in ether and would thus tend to increase the ether- 
extract (fat), if not combined with an alkali previous 
to the extraction. 



Chemical Analysis of Milk and Its Products. 229 

263. Specific gravity of butter milk. The specific gravity 
of butter milk (as well as of sour or loppered milk) is deter- 
mined by Weibull's method; a known volume of the milk is 
mixed with a certain amount (say 10 per cent.) of ammonia of 
a definite specific gravity, and the specific gravity of the liquid 
determined after thorough mixing and subsequent standing for 
an hour. If A designate the volume of butter milk taken, B that 
of ammonia, and (7 that of the mixture; and if furthermore jS 
designate the specific gravity of the butter milk, Si that of the 
ammonia, and S2 that of the mixture, we have 

CS2— Bsi 



A 

Klein* has modified this method by weighing the liquids, thus 
securing greater accuracy; 22 to 24 per cent. -ammonia is used, 
one-tenth as much oeing taken as the amount of milk weighed 
out. The results come uniformly .0005 too high, and this correc- 
tion should always be made. The following formula will give 
the specific gravity of the milk, which in case of careful work 
will be accurate to one-half lactometer degree; if the letters 
given above designate weights (instead of volumes as before) 
and specific gravities of the liquids, respectively, we have 



C _ ^ 

S2 Si 



264. Condensed milk. The same methods are, in gen- 
eral, followed in the analysis of condensed milk as with 
whole milk. Condensed milk is preferably diluted with 
five times its weight of water prior to the analysis, both 
because such a solution can be more easily handled 
than the undiluted thick condensed milk, and the errors 
of analysis are thereby reduced, and because the fat is 
not readily extracted except when the milk has been 

1 Milchzeitung, 1896, p. 656 ; see also De Koningh, Analyst, 1899, 
p. 142. 



230 Testing Milk and Its Froducts. 

diluted.^ The same constituents are determined as in 
case of whole milk, viz., solids, fat, casein and albumen, 
ash, milk sugar, and cane sugar (if any has been added 
to the milk). The cane sugar is determined by the dif- 
ference between the solids not fat and the sum of the 
casein, albumen, milk sugar and ash ; if the student has 
a knowledge of the manipulation of the polariscope and 
has had experience in gravimetric sugar analysis, the 
milk sugar is determined gravimetrically, and the cane 
sugar by the difference between the polariscope reading 
after inversion and the milk sugar present. 

The specific gravity of condensed mUk may be deter- 
mined by a method similar to that of McGill.^ 50 gr. 
of the thoroughly mixed sample are weighed into a 
tared beaker and washed with warm water into a 250 cc. 
flask, cooled to 60°, filled to the mark and carefully 
mixed. The specific gravity of this solution {a) is then 
taken and the original density is calculated by means 
of the following formula: 

Sp. gr. of condensed milk=^_- 

6-5a 

Concentration. The extent of concentration of con- 
densed milk may be determined approximately by the 
formula devised by McGill (loc. cit.) : 
Concentration (c)= ^ ^ 

aiS, 

where a and s designate the solids not fat and specific 
gravity, respectively, of the condensed milk, and a^ and 
Si the corresponding data for the milk used. If Sy= 

*A second extraction following leaching and subsequent drying of 
tlie tubes is necessary to extract all the fat in condensed milk ; see 
Bull. 104, Bur, of Chem., U. S. Dept. of Agr., p. 102 and 154. 

2 Bulletin 54, Laboratory Inland Rev. Dept., Ottawa, Canada. 



Chemical Analysis of Milk and Its Products. 231 

1.030 and a^=9 per cent., then c=-^ gives the con- 
centration. 

C— BtJTTEB. 

265. Sampling. A four- to eight-ounce sample of 
butter is melted in a tightly-clcsed pint fruit jar, 
shaken vigorously and cooled until the butter is hard- 
ened, the jar being shaken vigorously at short intervals 
during the cooling so as to keep the water of the butter 
evenly distributed in the mass (102). 

266. a. Determination of water. Small pieces of 
butter (about 2 grams in all) are taken from the sam- 
ple by means of a steel spatula and placed in glass tubes, 
seven-eighths of an inch in diameter and two and a half 
inches long, closed at the bottom by a layer of stringy 
asbestos, and filled two-thirds full of asbestos prepared 
as for milk analysis (252). The tubes are dried at 
100° C. in a steam oven, until no further loss in weight 
takes place, and are then cooled and weighed. The loss 
in weight shows the per cent, of water present. 

267. b. Fat. The tubes are placed in Caldwell ex- 
tractors and extracted for four hours with anhydrous 
ether ; the ether is then distilled off, and the flasks dried 
in the steam bath and weighed, the increase in weight 
giving the fat in the sample of butter weighed out. 

268. c. Casein. 10 grams of butter are weighed into 
a small beaker provided with a lip, and treated twice 
with about 50 cc. of gasoline each time; the solution is 
filtered off, and the residue transferred to a filter and 
dried; its nitrogen content is then determined by the 
Kjeldahl method (255). The nitrogen in the filter and 



232 Testing Milk and Its ProcHcts. 

the chemicals used is determined by blank trials and 
deducted. The nitrogen multiplied by 6.25 gives the 
casein in the butter. 

269. d. Ash. (1) 10 grams of butter are weighed 
into a porcelain dish and treated twice with gasoline, as 
in the preceding determination; the solution is filtered 
through an ash-free (quantitative) filter, and the filter 
when dry is transferred to the dish. The dish is heated 
in an air-bath for half an hour and then placed in a 
muffle oven, where the contents are burnt to a light 
grayish ash ; the dish is now cooled in a desiccator and 
weighed. The difference between this weight and that 
of the empty dish gives the amount of ash in the butter 
weighed out. 

270. (2) About two grams of butter are weighed into 
a small porcelain dish, half filled with stringy asbestos ; 
the dish is dried for half an hour in the water oven, 
and the fat then ignited with a match, the asbestos 
fibre serving as a wick. When the flame has gone out. 
the dish is placed in a muffle oven, and the residue 
carefully burnt to a grayish ash. After cooling, the dish 
is weighed, and the per cent, of ash in the butter calcu- 
lated as under method 1. 

271. Complete analysis of butter in the same sam- 
ple. , About 2 grams of the butter are weighed into a- 
platinum gooch half filled with stringy asbestos, and 
dried in a steam oven at 100° C. to constant weight, 
cooled and weighed. The difference gives water in the 
sample. The gooch is then treated repeatedly with 
small portions of gasoline, suction being applied, and 
again dried in the water oven, cooled, and weighed ; the 



Chemical Analysis of Milk and Us Products. 233 



fat in the sample is obtained from the difference be- 
tween this and the preceding weight. The gooch is 
then carefully heated at a low red heat until a light 
grayish ash is obtained; this operation is preferably 
done in a muffle oven to avoid a loss of alkali chlorids. 
The loss in weight gives the casein in the sample 
weighed out, and the increase in the weight of the gooch 
over that of the empty gooch wdth asbestos, gives the 
ash (mainly salt) of the butter. The salt in the ash 
may be dissolved out by hot water, and the chlorin 
content of the solution determined by means of a stand- 
ard silver-nitrate solution, using potassium chromate as 
an indicator (278). 

272. Creamery methods of estimating water in 
butter. A number of different methods have been pro- 
posed of late years 
for the rapid esti- 
mation of water in 
butter, the object 
sought being to en- 
able a buttermaker 
to ascertain the 
water content of his 
butter without much 
trouble or delay, 
and by using such simple apparatus as he is likely to 
have in the creamery or can easily procure at a low 
price. The subject of controlling the per cent, of water 
in butter has become more important than was earlier 
the case, through the passage of the pure-food law, 
and the promulgation of government food standards in 




Fig. 58a. 
for testing. 



Balance for weighing butter 



234 Testing Milk and Its Products. 

1906 (305) ; these measures have rendered the question 
of guarding against an excessive water content in the 
butter one of the greatest importance to all butter- 
makers. 

Most of the methods suggested for this purpose are 
essentially the common method of chemical analysis^ 
modified to meet the demands of every-day factory con- 
ditions. References to 
descriptions of the dif- 
ferent methods pro- 
posed are given below, 
and a few that are now 
used in factories and 
outside of chemical lab- 
•'■^^ oratories, are described 

Fig. 58b. Scale for weighing but- 
ter for testing. in detail. 

In all these rapid methods of determining the water 
content in butter, the sample of butter must be pre- 
pared so as to accurately represent the lot of butter 
sampled (see 102), and must be carefully weighed on a 
delicate scale (see figures 58a and b). Th-e directions, 
in so far as they are given in detail in the following, 
therefore, presuppose that a carefully prepared, fair 
sample has been obtained in all cases. 

273. Among the methods proposed for the rapid de- 
termination of the per cent, of water in butter that 
are adapted for use in creameries may be mentioned: 

Richmond's method,^ Carroll's tester,^ Geldard's bub- 

^ Dairy Chemistry, p. 252. 

*Dept. of Agr., Ottawa, Dairy Com'r Branch, bull. 6, pp. 10-11. 




\ib, 



i 



Chemical Analysis of Milk and Its Products. 235 

ter tester/ the Irish "common sense butter and cheese 
test," Dean's,^ Gray's,^ Pi trick's/ the Wisconsin high 
pressure oven method/ the Ames method/ and the 
Cornell moisture test.'^ 

Q The following four of these methods will be 

briefly described: 

274. a. Gray's method. This method, in- 
vented by Prof. C. E. Gray, formerly of 
the Dairy Division of the U. S. Dept. of Agri- 
culture, was published in 1906 ; the method 
consists of heating ten grams of butter in a 
special flask of about 70 cc. capacity (see fig. 
59) with 6 cc. of ''amyl reagent" (five parts 
of amyl acetate and one part amyl valerianate). 
The water is boiled out of the butter by heating 
over direct flame, and together with some of 
the reagent, is condensed, cooled, and meas- 
ured in a graduated tube attached to the flask. 
The accompanying illustration shows the ar- 
rangement of the distilling flask and the gradu- 
FiG. 5<j^ ated tube in which the water is measured. For 
u soused details of manipulation, reference is made to 
method, the Original publication, or to the files of our 
dairy press published during 1906-7.® 

1 Dept. of Agr„ Ottawa, Dairy Com'r Branch, bull. 14, pp. 6-8. 

2 Ontario Agr. College, rept. 1906, p. 120. 

» Circ. 100, Bur. An. Ind., U. S. Dept. of Agr. 

* Journal Am. Chem. Soc, 28, 1906, p. 1611. 
''Bull. 154, Wis. experiment station. 

8 Bull. 97, Iowa experiment station. 
^ Bull. 281, Cornell experiment station. 

• E. g., New York Produce Review, Jan. 16, 1907 ; American Cheese 
Maker, Jan., 1907. 




236 



Testing Milk and Its Products. 






A modification of the Gray method has been proposed 
by Mitchell and Walker of the Kingston (Ont.) Dairy 
School, and described as the Mitchell- Walker test.^ 

275. Patrick's method. Ten grams of butter are 
accurately weighed into a 300 cc. aluminum beaker 
(about 3 inches tall and 2 inches in diameter) ; this is 
held by means of a hand 
clamp over the flame of 
the alcohol lamp or a gas 
burner (see .fig. 60) and 
very carefuHy heated until 
all the water is expelled. 
The beaker is then cooled 
by sinking it to the rim in 
water of 50° to 60°, wiped 
dry, and the loss in weight 
calculated as water. If ten 

grams of butter weighed ^ig. 60. Aluminum beaker and 

° alcohal lamp used in the Patrick 

8.45 grams after heating, test. 

the loss in weight of 1.55 grams represents 15.5 per 
cent, of the weight of the sample, and the butter there- 
fore contained 15.5 per cent, of water.^ The results ob- 
tained by this method seldom vary more than .2 per 
cent, from those of chemical analysis, and often less 
than .1 per cent, when proper care in sampling and 
weighing has been taken. 
A few points need special attention in using this 

1 Bull, 167, Dairy Branch, Ont. Dept, of Agriculture. 

2 A convenient table showing per cents of moisture in butter direct 
when 9 to 10.15 grams are weighed out, has been published by the 
Copenhagen oxporimcnt station (62nd report; see N. Y. Produce Rev.. 
1008, p. 5M0). 




Chemical Analysis of Milk and Its Products. 237 

method : First, care must be taken not to heat the 
beaker too fast so that spattering occurs ; there is not so 
much danger from this source when an alcohol lamp is 
used as with a gas burner, which easily raises the tem- 
perature too high, causing a fine spray of material to 
be thrown about, and thus giving too high results for 
water content. Second, it is important to discontinue 
the heating at the exact point when all the water has 
been driven oft' and before burning of the non-fatty 
solids (casein, milk sugar, and organic acids) occurs, 
as indicated by a slight darkening in color. It is not 
necessary to cool the beakers in water, but they can be 
left to cool in the air. The determination of water in 
butter by this method can be finished in ten minutes 
or less by an experienced operator. 

The Irish test is similar to the method described in 
the preceding, difiPering from the same mainly in the 
shape of the aluminum dishes used. Modifications of 
this test have also been worked out by the Iowa and 
Cornell experiment stations, which are designed to pre- 
vent losses by spattering wlien the dish is heated. In 
the Ames method the aluminum dish containing the 
sample is heated with a paraffine bath, while in the Cor- 
nell test a thin sheet of asbestos is placed between the 
flame and the dish holding the samples. 

276. Dean's method. Three cc. of a melted sample 
Df butter are placed in an ordinary ''patty-pan" tin 
dish (about 2i/o inches in diameter and i/o inch deep) 
md accurately weighed; the dish is then placed in a 
steam oven provided with a pop safety valve, a steam 



238 Testing Milk and Its Products. 

pressure gauge, and a thermometer. The oven used 
by Professor Dean of Guelph (Ont.) Dairy School, the 
originator of this method, was 6x8 inches. It was made 
of galvanized iron by a local tin-smith at a cost of 
about $5.00, exclusive of safety valve and steam gauge, 
and was made to withstand a pressure of about 10 
pounds. After five or six hours' drying in the oven, 
the samples of butter are ready to be weighed, and the 
loss gives the amount of water present therein. The 
average results obtained by this method with nine sam- 
ples of butter came within .13 per cent, of those found 
by chemical analyses. 

The same method is recommended by the author for 
determining the per cent, of water in curd or cheese. 

277. The Wisconsin high-pressure oven method 
(see fig. 61). Either 10 or 50 grams of butter are 
weighed in a flat-bottomed tin or aluminum dish. This 
is placed in an oven heated by high pressure steam to a 
temperature of 240° to 280° F. The length of time re- 
quired to expel all the water from the butter will de- 
pend on the temperature of the oven and the diameter 
of the dish in which the butter is heated. If the dish 
is large enough to permit the butter to spread into 
a very thin layer and the temperature of the oven 
reaches 260° F., the water will be completely expelled 
in half an hour. Ovens of this construction have now 
been placed on the market by manufacturers of dairy 
supplies. A steam pressure of 60 lbs. and a tempera- 
ture of 280° F. may be obtained in such an oven; by 
employing the boiler pressure ordinarily used in a 



Chemical Analysis of Milk and Its Products. 239 

creamery, temperatures of 240° to 260° may be easily 
obtained. The temperature thus reached is sufficient to 
dry the butter completely within an hour, provided 
pans large enough to spread the butter in a thin layer 
are used. 

If 10 grams of butter are used in making tests, a 
more delicate scale is necessary than when 50 grams 
are taken. There are other advantages in using as large 
a quantity as 50 grams of butter for making tests of 
water. First, a sample can be __p^ 
weighed out directly from a 
package. Second, ordinary tin 
basins at least 5 inches in 
diameter can be used for dry- 
ing the butter. Third, scales 
with a graduated side beam 
and sensitive to .1 gram in- 
stead of those with smaller 
Loose weights can be used for 
weighing the butter. (See figs. 
58a and 58b.) 

278. Creamery methods of estimating salt in butter. I. 

The ordinary volumetric method used in chemical laboratories for 
determining the salt content of butter has been adapted for 
work in the creamery by Prof. Sammis.^ 5.1 grams of chemically 
pure nitrate crystals are dissolved in 250 cc. of water. Each cc. 
of this solution will represent 1 per ct. of salt when 17.6 cc. of 
the liquid are measured which is obtained by shaking 10 grams 
of butter with 250 cc. of clean, warm water. The silver nitrate 
solution is added from a 25 or 50 cc. burette divided into tenths 
of a cubic centimeter. One or two drops of the usual indicator 




Fig. 61. Tne Wisconsin high- 
pressure oven. 



' rirc. 14, Wisconsin expt. station. 



240 Testing Milk and Its Products. 

employed (1 oz. potassium cliromate dissolved in 100 cc. of water) 
are added prior to the titration. 

II. The use of silver nitrate tablets for making standard 
solutions for volumetric determinations of salt in butter was 
proposed by Prof. A. Vivian and C. L. Fitch in 1901.^ The tab- 
lets have not been on the market during late years. 

278a. Shaw's test for fat and salt in butter. R. H. 
Shaw has devised a method for determining the per- 
centages of fat and salt in the same sample of butter 
which has considerable merit. For description of this 
method see Circ. 202, Bur. of Animal Ind., U. S. Dept. 
of Agriculture. 

Detection of Artificial Butter. 

279. Determination of the specific gravity of the fil- 
tered butter fat serves as a good preliminary test. A 
number of practical methods for the detection of artifi- 
cial butter have been proposed, but they are either 
worthless for the examination of samples containing a 
considerable proportion of natural butter, or give satis- 
factory results only in the hands of experts. The Reich- 
ert-Meissl method given in detail below is the standard 
method the world over, and the results obtained by it 
are accepted in the courts. 

280. Filtering the butter fat. The butter to be ex- 
amined is placed in a small narrow beaker and kept at 
60° C. for about two hours. The clear supernatant fat 
is then filtered through absorbent cotton into a 200 cc. 
Erlenmeyer flask, taking care that none of the milky 
lower portion of the contents of the beaker be poured 
on the filter. In sampling the butter fat, it is poured 

» 1 Wis. experiment station, report 17, pp. 98-101 ; Hoard's Dairyman, 
February 15, 1901, "Uniform Salting of Butter." 



Chemical Analysis of Milk and Its Products. 241 

back and forth repeatedly from a small warm beaker 
into the flask, and the quantity wanted is then drawn 
off with a warm pipette. 

281. Specific gravity. This is generally determined 
at 100° C. The method of procedure is similar to that 
described under milk (248). The picnometer (capacity 
about 25 cc.) is filled with dry filtered butter fat, free 
from air bubbles; the fat is heated for 30 minutes in a 
beaker, the water in which is kept boiling. On cooling, 
the weight of picnometer and fat is obtained, and by 
calculation as usual, the specific gravity of the fat. 

The specific gravity of pure natural butter fat at 
100° C. ranges between .8650 and .8685, while artificial 
butter fat (i. e., fat from other sources than cow's milk) 
has a specific gravity at 100° C. of below .8610, and gen- 
erally about .85. 

282. Reichert-MeissI method (Volatile Acids.) 5.75 
cc. of fat are measured into a strong 250 cc. weighed 
saponification flask, by means of a pipette marked to 
deliver this amount, and the flask when cool is weighed 
again. 20 cc. of a glycerol-soda solution (20 cc. of 
soda solution (1:1) to 180 cc. of pure glycerol), are then 
added to the flask and the flask is heated over a naked 
flame or hot asbestos plate until complete saponification 
has taken place, as shown by the mixture becoming per- 
fectly clear. If foaming occur, the flask is shaken 
gently. 

135 cc. of recently-boiled distilled water are now 
added, drop by drop, at first, to prevent foaming, and 
when the solution is clear, cooled to about 70° C. ; 5 cc. 
of dilute sulfuric acid (200 cc. ccnc. H2SO4 per liter) are 

16 



242 Testing Milk and Its Products. 

added to the soap solution to decompose the soap into 
free fatty acids and glycerol. A few pieces of pumice 
stone (prepared by throwing the pieces at white heat 
into distilled water and keeping them under water until 
used) are added, the flask connected with a glass con- 
denser, heated slowly till boiling begins, and the con- 
tents then distilled at such a rate as will bring 110 cc. 
of the distillate over in as nearly thirty minutes as pos- 
sible. 

The distillate is mixed thoroughly and filtered 
through a dry filter; 100 cc. of the filtrate are poured 
into a 250 cc. beaker and titrated with a deci-normal 
barium-hydrate solution, half a cubic centimeter of phe- 
nolphtalein solution being used as an indicator. A blank 
test is made in the same manner as described, and the 
amount of alkali solution used deducted from the re- 
sults obtained with the samples analyzed. The number 
of cubic centimeters of barium-hydrate solution used is 
increased by one-tenth, and the so-called Reichert or 
Reichert-Meissl number thus obtained. 

The Keichert number for pure butter fat will ordi- 
narily come above 24 cc. and may go over 30 cc ; butter 
fat from stripper cows will have a low Reichert num- 
ber. Pure oleomargarine will have a Reichert number 
of 1 to 2 cc. ; and mixtures of artificial and natural but- 
ter will give intermediate numbers. 

Tests for the Detection op Oleomargarine or Reno- 
vated Butter. 
283. The boiling test.^ A piece of butter of the size 
of a small chestnut is melted in an ordinary tablespoou 

1 Patrick, Household tests for the detection of oleomargarine and 
renovated butter, Farmer's Bulletin, No. 131. For detection and 



Chemical Analysis of Milk and Its Products. 243 

(or a small tin dish) at a low heat, stirring with a splin- 
ter of wood. The heat is increased until as brisk a boil 
as possible, and after boiling has begun, the melted mass 
is stirred thoroughly two or three times, always shortly 
before boiling ceases. Oleomargarine and renovated 
butter will boil noisily, sputtering like a mixture of 
grease and water when boiled, and will produce but 
little or no foam. Renovated butter produces usually a 
very small amount of foam, while genuine butter boils 
with less noise and produces an abundance of foam. 

284. The Waterhouse test for distinguishing oleo- 
margarine and renovated butter.^ Half fill a 100 cc. 
beaker with sweet skim milk (or distilled water), heat 
nearly to boiling and add 5 to 10 grams of butter or 
oleomargarine. Stir with a small wooden stick of about 
the size of a match until the fat is melted ; the beaker is 
then placed in ice water, and the milk (or water) stirred 
until the temperature falls sufficiently for the fat to 
congeal. If oleomargarine, the fat can now be easily 
collected into one lump by means of the stick, while if 
genuine or renovated butter, the fat will granulate and 
can not be so collected. - 

D.— Cheese. 

For method of sampling, see par. 104. 

285. a. Water. Five grams of cheese cut into very 
thin slices are weighed into a small porcelain dish filled 
about one-third full with freshly-ignited stringy asbes- 

exnmination of renovated or "process" butter, see also Cochrnn. Journ 
Franlh Tnst.. IROO. p. 04: AnaU/st. 1899. p. 88. 

1 Farmers' Bulletin No. 131, p. 7. 

2 For tests for artificial coloring matter in oleomargarine, see Circ. 
629, Com. of Internal Rev., Treasury Dopt. 



244 Testing Milk and Its Products. 

tos; the dish is placed in a water oven and heated for ten 
hours. The loss in weight is taken to represent water. 
(See also Dean's method for determining water in but- 
ter, curd and cheese, par. 276.) 

286. b. Fat. About 5 grams of cheese are ground 
finely in a small porcelain mortar with about twice its 
weight of anhydrous copper sulfate, until the mixture is 
of a uniform light blue color and the cheese evenly dis- 
tributed throughout the mass. The mixture is trans- 
ferred to a glass tube of the kind used in butter analysis 
(263), only a larger size; a little- copper sulfate is placed 
at the bottom of the tube, then the mixture containing 
the cheese, and on top of it a little extracted absorbent 
cotton or ignited stringy asbestos ; the tube is placed in 
an extraction apparatus and extracted with anhydrous 
ether for fifteen hours. The ether is then distilled off, 
the flasks dried in a water oven at 100° C. to constant 
weight, cooled and weighed. The method is apt to give 
too low results and, therefore, not to be preferred to 
the Babccck test for cheese (105). 

287. c. Casein (total «jiitrogenX6.25). About 2 grams 
of cheese are weighed out on a watch glass and trans- 
ferred to a Jena nitrogen flask, and the nitrogen in the 
sample determined according to the Kjeldahl method 
(253) ; the percentage of nitrogen multiplied by 6.25 
gives the total nitrogenous components of the cheese. 

288. d. Ash. The residue from the water determina- 
tion is taken for the ash ; it is preferably set fire to, in 
the same manner as explained under determination of 
ash in butter (270), before it is placed in the muffle 
oven and incinerated. The increase in the weight above 



Chemical Analysis of Milk and Its Products. 245 

that of the empty dish-f asbestos, gives the amount of 
ash in the sample weighed out. 

289. e. Other constituents. The sum of the percent- 
ages of water, fat, casein and ash, subtracted from 100, 
will give the per cent, of other constituents, organic 
acids, milk sugar, etc., in the cheese. 

Detection of Oleomargarine Cheese ("Filled'' 

CHi'.ESE.) 

290. About 25 grams of finely-divided cheese are ex- 
tracted with ether in a Caldwell extractor or a paper 
extraction cartridge; the ether is distilled off, and the 
fat dried in the water oven until there is no further 
loss in weight. 5.75 cc. of the clear fat are then meas- 
ured into a 250 cc. saponification flask and treated ac- 
cording to the Reichert-Meissl method, as already ex- 
plained under Detection of Artificial Butter (282).^ 

Tests for Adulteration of Milk and Cream. 

291. Use of the ref ractometer. The immersion re- 
fractometer furnishes a delicate apparatus for the de 
tection of watered milk.^ 100 cc. of milk and 2 cc. of 
25% acetic acid are heated for twenty minutes at 70° C. 
This is then placed on ice for ten minutes and filtered. 
The refractometer reading of the clear filtrate is then 
taken at 20° C. If this reading is above 40 the milk is 
not watered, while figures below 40 show adulteration by 
watering. 

291a. The nitric acid test may prove useful as cor- 
roborative evidence that a sample of milk has been 

1 See Arb. Kais. Ges.-Amt., 14, 506-598. 

2 Leach, Food Analysis, 2nd ed., p. 168. See also Jr. Ind. and Eng. 
Chem., 1911, p. 44 and p. 573. 



246 Testing Milk and Its Products. 

watered (126). Normal fresh milk does not contain 
nitrates, while common well-water, particularly on 
farms where precautions to guard against contamina-' 
tion of the water supply have not been taken, in gen- 
eral contains appreciable amounts of nitrates, nitrites 
and ammonia compounds, and watered milk will, there- 
fore, in such cases also contain nitrates.^ The method 
for detection of small amounts of nitrates in milk, as 
given by Richmond^ is as follows: Place a small quan- 
tity of diphenylamin at the bottom of a porcelain dish, 
and add to it about 1 cc. of pure H^SOj (cone.) ; allow 
a few drops of the milk serum (obtained by adding a 
little acetic acid to the milk and warming) to flow down 
the sides of the, dish and over the surface of the acid. 
If a blue color develops in the course of ten minutes, 
though it may be faint, it shows the presence of nitrates ; 
after ten minutes a reddish-brown color is always de- 
veloped from the action of the acid on the serum. 
There should be no difficulty in detecting an addition of 
10 per cent, of water to the milk by this test, if the 
water added contained 5 parts of nitric acid, or more, 
per 100,000. 

The following test for nitric acid is proposed by Mc- 
Kay and Bouska: About 5 cc. of milk is placed in a 
test tube. Some Kaniss' reagent (about 1 part formal- 
dehyd in 500 cc. C. P. H2SO4) is poured down the side 
of the tube so it will form a layer under the milk. If 
nitrates or nitrites are present, a violet ring will form 
at the place of contact. This is Hehner's test for for- 
maldehyd reversed, see (304). 

1 TJffelmann, Deutsche Vierteljahresschr. f. off. Ges.-pfl., 15, p. 663. 

2 The Analyst, 1893, p. 272. 



Chemical Analysis of Milk and Its Products. 247 

292. Besides by the methods given in the preceding 
(pp. 121-127), watering or skimming of milk may be de- 
tected by determining the specific gravity of a, the skim 
milk, h, the milk serum, and c, the whey. 

a. Specific gravity of skim milk. The milk is set in a flat 
porcelain or glass dish for 12 to 24 hours in a cold room; the layer 
of cream formed is then skimmed off, and the sp. gr. of the skim 
milk determined at 60° F. Skim milk has a sp. gr. of .002 to 
.0035 (2 to 3.5 lactometer degrees) above that of the correspond- 
ing whole milk; a smaller difference than this indicates that the 
milk was skimmed. If both skimming and watering had been 
practiced, the difference given above might be obtained, but the 
analysis of the milk would in such case easily disclose the adul- 
teration. 

h. Specific gravity of the milk serum. To 100 cc. milk 2 
cc. of 20 per cent.-acetic acid are added, and the mixture heated 
in a covered beaker or closed flask for 5-10 min. on a water-bath 
at 55-65° C. After cooling, the milk serum is filtered off and its 
sp. gr. determined at 60° F. In case of pure milks, the sp. gr. 
of the milk serum (at 60°) will come above 1.0270. Serum from 
normal milk contains 6.3 to 7.5 per cent, solids and .22 to .28 
per cent, fat; by the addition of 10 per cent, of water, the 
solids in the serum are lowered .3 to .5 per cent., and the sp. gr., 
.0005.* 

c. Specific gravity of whey. 500 cc. of milk are warmed in 
water of 40-50° C. until its temperature is 35° C; one-half cc. 
of rennet extract (12-15 drops) is added, and the milk stirred 
thoroughly. After allowing the curd to solidify for 10 minutes, 
it is cut and the whey filtered off through several layers of cheese 
cloth. The whey must be clear; it is cooled to 60° F. and its 
sp. gr. determined. The sp. gr. of whey from normal- milk ob- 
tained in the manner given will range between 1.027 and 1.031. 
A sp. gr. of 1.026 or below indicates watering. An addition of 
4 per cent, of water lowers the sp. gr. of the whey about 1 lac- 
tometer degree.* 



^ Konig, Menschl. Nahrungsmittel, II, p. 276. 
2 Siats, Unters. landw. wicht. Stofife, p. 88. 



248 Testing Milk and Its Products. 

293. Detection of coloring matter. Milk which has 
been watered or skimmed, or both, is sometimes further 
adulterated by unscrupulous milk dealers by an addi- 
tion of a small quantity of cheese color; this will mix 
thoroughly with the milk, and, if added judiciously, will 
impart a rich cream color to it. The presence of for- 
eign coloring matter in milk is easity shown by shaking 
10 cc. of the milk with an equal quantity of ether; on 
standing, a clear ether solution will rise to the surface; 
if artificial coloring matter has been added to the milk, 
the solution will be yellow colored, the intensity of the 
color indicating the quantity added; natural fresh 
milk will give a colorless ether solution. 

A method gived by Wallace^ is claimed to detect one 
part of coloring matter in 100,000 of milk. 

Inorganic coloring matter like chromates and bi-chro- 
mates have, although fortunately rarely, been used to 
impart a rich color to adulterated milk or poor cream. 
Chrcmates may be detected by the reddish yellow color 
produced when a little 2 per cent.-silver nitrate solution 
is added to a few cubic centimeters of the milk. 

294. Detection of pasteurized milk or cream. Prof. 
Storch, of Copenhagen, Denmark,^ in 1898, published a 
simple method for ascertaining whether milk, cream, 
or other dairy products have been heated to at least 
176° F. (80° C). The test is made as follows: A 
teaspoonful of the milk is poured into a test tube, and 
1 drop of a weak solution of peroxid of hydrogen (2 
per cent.) and 2 drops of a paraphenylenediamin-solu- 

1 N. J. Dairy Commissioner, report 1896, p. 36. 

2 40th report, Copenhagen experiment station. 



Chemical Analysis of Milk and Its Products. 249 

tion (2 per cent.) are added. The mixture is then 
shaken; if a dark violet color appears at once, the milk 
has not been heated, or at any rate not beyond 176° F. 
If a sample of butter is to be examined, 25 grams are 
placed in a small beaker and melted by being placed in 
water of 60° C. The clear butter fat is poured off, and 
the remaining liquid is diluted with an equal volume of 
water. The mixture thus obtained is examined as in 
case of milk. 

Guaiacum tincture has also been recommended for the 
detection of pasteurized cream or milk; this solution is 
easily obtained, keeps well, and is convenient to use 
(McKay). 

295. Boiled milk. The preceding tests will serve to 
distinguish between raw and boiled milk, and also to 
ascertain if milk has been adulterated with diluted con- 
densed milk. To what extent such an adulteration can 
be practiced without being detected by this or similar 
tests, has not been determined, but if a control test be 
made at the same time with a sample of milk of known 
purity, a small admixture of boiled (or diluted con- 
densed) milk can doubtless be detected.^ 

296. Gelatine in cream. This method of adultera- 
tion is sometimes practiced in the city cream trade, to 
impart stiffness and an appearance of richness to the 
cream. To detect the gelatine, a quantity of the sus- 
pected cream is mixed with warm water, and acetic acid 
is added to precipitate the casein and fat (1.5 cc. of 10 
per cent.-acetic acid per 10 cc. of cream is sufficient). 

1 See also Siats, Unters. landw. wicht. Stofife, p. 60, and Molkerei- 
Ztg. (Hildeshelm), 1899, p. 677. 



250 Testing Milk and Its Products. 

The precipitate is filtered off, and a few drops of a 
strong tannin solution are added to the clear filtrate. 
Pure cream will give a slight precipitate, while in the 
presence of gelatine a copious precipitate will come 
down. 

The picric-acid method has also been proposed for 
the detection of small quantities of gelatine in cream.^ 

297. Starch in cream. Starch is mentioned in the 
dairy literature as an adulterant of milk and cream. It 
is doubtful, however, if it is ever used for this purpose 
at the present time. In the case of ice-cream, on the 
other hand, a small quantity of corn starch is often 
added to thicken the milk used. It may in such a case 
be readily detected by means of the iodin reaction. A 
solution of iodi*i will produce a deep blue color in the 
presence of starch ; a small amount of iodin is taken up 
by the cream before -the blue coloration appears. 

298. Macroscopic impurities (particles of hay, litter, 
woolen or cotton fibres, dung, etc.). These impurities 
may be separated by repeated dilution of the milk with 
pure distilled water, leaving the mixture undisturbed 
for a couple of hours each time before the liquid is 
syphoned off. When the milk has been entirely re- 
moved in this manner, the residue is filtered off, dried 
and weighed. A quart of milk or cream should not 
give any visible sediment on standing for several hours. 

A simple and striking method of showing dirt 
in milk has been suggested by Gerber. About a pint of 
milk is poured into an inverted bottomless long-necked 

1 The Analyst, 1897, p. 320. 



Chemical Analysis of Milk and Its Products. 251 

bottle, over the mouth of which a piece of cotton is 
placed. The milk will filter through, leaving the dirt 
on the cotton, which is then removed and can be shown 
to the producer cf the milk.^ 

A modification of the apparatus used has been de- 
scribed in publications of the Wisconsin experiment 
station.- 

Detection of Preservatives in Dairy Products. 

299. a. Boracic acid {borax, borates, preservaline, 
etc.). 100 cc. of milk are made alkaline with a soda 
or potash solution, and then evaporated to dryness and 
incinerated. The ash is dissolved in water to which a 
little hydrochloric acid has been added, and the solu- 
tion filtered. A strip of turmeric paper moistened with 
the filtrate will be colored reddish brown when dried at 
100° C. on a watch glass, if boracic acid is present. 

If a little alcohol is poured over the ash to which con- 
centrated sulfuric acid has been added, and fire is set 
to the alcohol, this will burn with a yellowish green 
tint, especially noticeable if the ash is stirred with a 
glass rod and when the flame is about to go out. 

300. The following modification of the first test given is said 
to show the presence of only a thousandth of a grain of borax 
in a drop of milk (about .15 per cent.) :^ 

Place in a porcelain dish one drop of milk with two drops of 
strong hydrochloric acid and two drops of saturated turmeric 
tincture; dry this on the water bath, cool and add a drop of 
ammonia by means of a glass rod. A slaty blue color changing 
to green is produced if borax is present.* 



1 Hoard's Dairyman, Nov. 29, 1907. . 

*Buil. 195 and Circular 41. 

» N. J. Dairy Commissioner, report, 1896 p. 36. 

* See also par. 151. 



252 Testing Milk and Its Products. 

301. b. Bi-carbonate of soda. 100 cc. of milk to 
which a few drops of alcohol are added, are evaporated 
and carefully incinerated; the proportion of carbonic 
acid in the ash as compared with that of milk of known 
purity is determined. If an apparatus for the deter- 
mination of carbonic acid is available, like the Scheibler 
apparatus, etc., the per cent, of carbonic acid per gram 
of ash (and quart of milk) can be easily ascertained. 
Normal milk ash contains only a small amount of car- 
bonic acid (less than 2 per cent.), presumably formed 
from the citric acid of the milk in the process of incin- 
eration. 

The following qualitative test is easily made: To 10 
cc. of milk add 10 cc. of alcohol and a little of a one 
per cent, solution of rosolic acid (corallin). Pure milk 
will give a brownish yellow color ; milk to which soda has 
been added, a rose red color. A control experiment with 
milk of known purity should be made. 

302. c. Fluorids. 100 cc. of milk are evaporated in 
a platinum or lead crucible, and incinerated; the ash is 
made strongly acid with concentrated sulfuric acid. If 
fluorids are present hydrofluoric acid will be generated 
on gentle heating and will be apparent from its etching 
a watch glass placed over the crucible.^ 

303. d. Salicylic acid {salicylates, etc.). 20 cc. of 
milk are acidulated with sulfuric acid and shaken with 
ether; the ether solution is evaporated, and the residue 
treated with alcohol and a little iron-chlorid solution; 

» Chromates in dairy products may be readily determined by the use 
of a silver-nitrate solution, see Molkerei-Ztg. (Berlin) 1899, p. 603. 



Chemical Analysis of Milk and Its Products. 253 

a deep violet color will be obtained in the presence of 
salicylic acid. 

304. e. Formaldehyde (a forty-per cent, solution in 
water) . 

The following method by Hehner is stated to show 
the presence of one part of formaldehyde in 200,000 
parts of milk : the milk is diluted with an equal volume 
of water, and strong H.SO4 (sp. gr. 1.82-1.84) is added. 
A violet ring is formed at the junction of the two 
liquids if formaldehyde is present ; if not, a slight green- 
ish tinge will be seen. The violet color is not obtained 
with milk containing over .05 per cent, formaldehyde.* 

The same color reaction is obtained in the Babcock 
test and is easily recognized by persons familiar with 
milk testing when their attention has once been called 
to the characteristic color. 

An adulteration of milk with formaldehyde may be 
readily detected by the following method, which will 
show the presence of only a trace of formaldehyde in 
the milk. 5 cc. of milk is measured into a white porce- 
lain dish, and a similar quantity of water added. 10 
cc. of HCl containing a trace of FCoClo is added, and 
the mixture is heated very slowly. If formaldehyde is 
present, a violet color will be formed. 

1 Chem. News, 1896. No. 71 ; Milchzeitung, 1896, 491 ; 1897, 40. 
667 ; The Analyst, 1895, 152, 154, 157 ; 1896, 285. 



305. GOVERNMENT STANDARDS OF PURITY 
FOR MILK AND ITS PRODUCTS/ 



a. MILKS. 

1. Milk is the fresh, clean, lacteal secretion obtained by the 
complete milking of one or more healthy cows, properly fed 
and kept, excluding that obtained within fifteen days before and 
ten days after calving, and contains not less than eight and one 
half (8.5) per cent, of solids not fat, and not less than three 
and one-quarter (3.25) per cent, of milk fat. 

2. Blendid milk is milk modified in its composition so as to 
have a definite and stated percentage of one or more of its con 
stituents. 

3. Skim milk is milk from which a part or all of the cream 
has been removed and contains not less than nine and one-quarter 
(9.25) per cent, of milk solids. 

4. Pasteurized milk is milk that has been heated below boil- 
'ng but sufficiently to kill most of the active organisms present 
and immediately cooled to 50° Fehr. or lower. 

5. Sterilized milk is milk that has been heated at the tem 
perature of boiling water or higher for a length of time suffi 
cient to kill all organisms present. 

6. Condensed milk, evaporated milk, is milk from which a 
considerable portion of water has been evaporated and contains 
not less than twenty-eight (28) per cent, of milk solids, of which 
not less than twenty-seven and five-tenths (27.5) per cent, is 
milk fat. 

7. Sweetened condensed milk is milk from which a consid- 
erable portion of water has been evaporated and to which sugar 
(sucrose) has been added, and contains not less than twenty- 
eight (28) per cent of milk solids, of which not less than 
twenty-seven and five-tenths (27.5) per cent, is milk fat. 

1 Circular No. 19, Office of the Secretary, U. S. Dept. of Agricultur<\ 
June 26. 1906. 



Government Standards of Purity. 255 

8. Condensed skim milk is skim milk from which a consid- 
erable portion of water has been evaporated. 

9. Buttermilk is the product that remains when butter is re- 
moved from milk or cream in the process of churning. 

10. Goat's milk, ewe's milk, etc., are the fresh, clean, lac- 
teal secretions, free from colostrum, obtained by the complete 
milking of healthy animals other than cows, properly fed and 
kept, and conform in name to the species of animal from which 
they are obtained. 

b. CREAM. 

1. Cream is that portion of milk, rich in milk fat, which 
rises to the surface of milk on standing, or is separated from it 
by centrifugal force, is fresh and clean and contains not less 
than eighteen (18) per cent, of milk fat. 

2. Evaporated cream, clotted cream, is cream from which 
a considerable portion of water has been evaporated. 

C. MILK FAT OR BUTTER PAT. 

1. Milk fat, butteD fat, is the fat of milk and has the Reich- 
ert-Meissl number not less than twenty-four (24) and a specific 

gravity of not less than 0.905 (f^) 

d. BUTTER. 

1. Butter is the clean, non-rancid product made by gather- 
ing in any manner the fat of fresh or ripened milk or cream 
into a mass, which also contains a small portion of the other 
milk constituents, with or without salt, and contains not less 
than eighty-two and five^tenths (82.5) per cent, of milk fat. By 
acts of Congress approved August 2, 1886, and May 9, 1902, 
butter may also contain added coloring matter. 

2. Renovated butter, process butter, is the product made 
by melting butter and reworking, without the addition or use of 
chemicals or any substances except milk, cream, or salt, and 
contains not more than sixteen (16) per cent, of water and at 
least eighty-two and five- tenths (82.5) per cent, of milk fat. 



256 Testing Milk and Its Products. 

e. CHEESE. 

1. Cheese is the sound, solid, and ripened product made from 
milk or cream by coagulating the casein thereof with rennet or 
lactic acid, with or without the addition of ripening ferments 
and seasoning, and contains, in the water-free substance, not less 
than fifty (50) per cent, of milk fat. By act of Congress, ap- 
proved June 6, 1896, cheese may also contain added coloring 
matter. 

2. Skim milk cheese is the sound, solid, and ripened product, 
made from skim milk by coagulating the casein thereof with 
rennet or lactic acid, with or without the addition of ripening 
ferments and seasoning. 

3. Goat's milk cheese, e\ve's milk cheese, etc., are the 

sound, ripened products made from the milks of the animals 
specified, by coagulating the casein thereof with rennet or lactic 
acid, with or without the addition of ripening ferments and 
seasoning. 

f. ICE CREAMS. 

1. Ice cream is a frozen product made from cream and sugar, 
with or without a natural flavoring, and contains not less than 
fourteen (14) per cent, of milk fat. 

2. Fruit ice creami is a frozen product made from cream, 
sugar, and sound, clean, mature fruits, and contains not less than 
twelve (12) per cent, of milk fat. 

3. Nut ice cream is a frozen product made from cream, 
sugar, and sound, non-rancid nuts, and contains not less than 
twelve (12) per cent, of milk fat. 

g. MISCELLANEOUS MILK PRODUCTS. 

1. Whey is the product remaining after the removal of fat 
and casein from milk in the process of cheese-making. 

2. Kumiss is the product made by the alcoholic fermentation 
of mare's or cow's milk. 



306. STANDARDS FOR BABCOCK 
GLASS WARE. 

(Adopted by tlie Association of OflSeial Agricultural Chemists of 

North America.) 



Sec. 1. The unit of graduation for all Babcock glassware 
shall be the true cubic centimeter (.998877 gram of water at 

4° C). 

(a) With bottles, the capacity of each per cent, on the scale 
shall be two-tenths (0.20) cubic? centimeter. 

(b) With pipettes and acid measures the delivery shall be the 
intent of the graduation and the graduation shall be read with 
the bottom of the meniscus in line with the mark. 

Sec. 2. The official method for testing bottles shall be cali- 
bration with mercury (13.5471 grams of clean, dry mercury at 
20" C. carefully weighed on analytical balances, to be equal to 
5 per 'cent, on the Babcock scale), the bottles being previously 
filled to zero with mercury. 

Sec. 3. Optional methods.— The mercury and cork, alcohol and 
burette, and alcohol and brass plunger methods may be employed 
for the rapid testing of Babcock bottles, but the accuracy of all 
questionable bottles shall be determined by the official method. 

Sec. 4. The official method for testing pipettee and acid 
measures shall be calibration by measuring in a burette the 
quantity of water (at 20° C.) delivered. 

Sec. 5. The limits of error.— (a) For Babcock bottles shall 
be the smallest graduation on the scale, but in no case shall it 
exceed five-tenths (0.50) per cent., or for skim milk bottles one- 
hundredth (0.01) per cent. 

(b) For full-quantity pipettes, it shall not exceed one-tenth 
(0.10) cubic centimeter, and for fractional pipettes, five-hun- 
dredths (0.05) cubic centimeter. 

(c) For acid measures it shall not exceed two-tenths (0.20) 
cubic centimeter. 



17 



307. SPECIFICATIONS FOR STANDARD 
BABCOCK GLASS WARE. 

(Adopted by the Official Dairy Instructors' Association, 1911) 



I. Milk Test Bottle. 8% 18 gram, so-ealled 6-inch. 
Graduation: The total per cent graduation shall be 8. The 

graduated portion of the neck shall have a length of not less than 
63.5 mm. (2^/^ inches). The graduation shall represent whole per 
cent, five-tenths per cent and tenths per cent. The tenths per cent 
graduations shall not be less than 3 mm. in length; the five-tenths 
per cent graduations shall be 1 mm. longer than the tenth per cent 
graduations, projecting 1 mm. to the left; the whole per cent 
graduations shall extend one-half, way around the neck to the right 
and projecting 2 mm. to the left of the tenths per cent gradua- 
tions. Each per cent graduation shall be numbered, the number 
being placed on the left of the scale. The error at any point of 
the scale shall not exceed one-tenth per cent. 

Neck: The neck shall be cylindrical for at least 9 mm. below 
the lowest and above the highest graduation mark. The top of 
the neck shall be flared to a diameter of not less than 10 mm. 

Bulb : The capacity of the bulb up to the junction of the neck 
shall not be less than 45 cc. The shape of the bulb may be either 
cylindrical or conical, with the smallest diameter at the bottom. 
If cylindrical, the outside diameter shall be between 34 and 36 
mm.; if conical, the outside diameter of the base shall be between 
31 and 33 mm., and the maximum diameter between 35 and 37 mm. 

The Charge of the bottle shall be 18 grams. 

The Total Height of the bottle shall be between 150 and 165 
mm. (5% and 6^ inches). 

Each bottle shall bear a permanent identification number. 

II. Cream Test Bottles. 50% 9-gram, so-called 6-inch, and 
50% 9-gram, so-called 9-inch. 

A. 50% 9- gram, so-called 6-inch. 

Graduation: The total per cent graduation shall.be 50. The 
graduated portion of the neck shall have a length of not less 
than 63.5 mm. (2^4 inches). The graduation shall represent 5 
per cent, 1 per cent and five-tenths per cent. The five-tenths per 
cent graduations shall be at least 3 mm. in length; the 1 per cent 



Specifications for Glassware. 258a 

graduations shall be 2 mm. longer than the five-tenths per cent 
graduations, projecting 2 mm. to the left; the 5 per cent gradua- 
tions shall extend half way around the neck to the right and pro- 
ject 4 mm. to the left of the five-tenths per cent graduations. 
Each 5 per cent graduation shall be numbered, the number being 
placed on the left of the scale. The error at any point of the 
scale shall not exceed five-tenths per cent. 

Neck: (Same as standard milk test bottle.) The neck shall 
be cylindrical for at least 9 mm. below the lowest and above the 
highest graduation mark. The top of the neck shall be flared to a 
diameter of not less than 10 mm. 

Bulb: (Same as standard milk test bottle.) The capacity of 
the bulb up to the junction of the neck shall not be less than 
45 cc. The shape of the bull) may be either cylindrical or conical, 
with the smallest diameter at the bottom. If cylindrical the out- 
side diameter shall be between 34 and 36 mm.; if conical, the 
outside diameter of the base shall be between 31 and 33 mm. and 
the maximum diameter between 35 and 37 mm. 

The Charge of the bottle shall be 9 grams. All bottles shall 
bear on top of the neck above the graduations in plainly legible 
characters, a mark defining the weight of the charge to be used 
(9 grams). 

The Total Height of the bottle shall be between 150 and 165 
mm. (5% and 6% inches). (Same as standard milk test bottles.) 

Each bottle shall bear a permanent identification number. 

B. 50% 9-gram, so-called D-inch. 

The same specifications in every detail as specified for the 50% 
9-gram 6-inch cream test bottle shall apply to the 9-inch bottle, 
with the exception, however, that the total height of this bottle 
shall be between 210 and 225 mm. (8Vi and 8% inches). 

III. The Standard Babcock Pipette. Total length of 
pipette not more than 330 mm. (13^/4 inches). Outside diameter 
of suction tube 6 to 8 mm. Length of suction tube 130 mm. Out- 
side diameter of delivery tube, 4.5 to 5.0 mm. Length of deliv- 
ery tube, 100 to 120 mm. Distance of graduation mark above bulb, 
30 to 60 mm. Nozzle straight. Delivery 17.6 cc. of water at 20 
degrees C. in 5 to 8 seconds. 

In view of the fact that the skimmilk bottle can give only ap- 
proximate quantitative results, it should be given no consideration 
as a standard bottle. 



APPENDIX. 



Table I. Composition of milk and its products. 



Cow's milk. 



Colostmm milk 

Cream 

Cream, Cooley 

Skim milk (gravity) . . 

Skim milk (centrifugal) 

Bntter milk 

<i It 

Whey 



Condensed milk, 

(no sugar added) . . . 
Condensed milk, 

(sugar added) 

Butter, salted 

* ' sweet cream . . 

" sour cream.. . 

" unsalted 

" World's Fair. 1893 
Cheese, cream 

** full cream... . 

* * eheddar, green 

" eheddar, cured 

" World's Fair 
Mam'th, 1893 

•* half -skim .... 

" skim 

** centrifugal skim.. 



No. of 
analfses 



793 



6,552 
2,173 
200,000 
42 
43 
203 
56 
354 



57 
31 
46 



36 

64 

1,676 

10 

11 

242 
350 
127 
143 



27 

1 
21 
41 



Water 
pr. ct. 

87.17 
87.75 
87.10 
86.48 
87.10 
74.57 
68.82 
73.90 
90.43 
90.52 
90.30 
90.12 
91.67 
93.38 
93.12 

58.99 

25.61 
11.95 
12.93 
13.08 
13.07 
11.57 
36.33 
38.00 
36.84 
34.38 

32.06 
39.79 
46.00 
50.5 



Fat 

pr. ct. 

3.69 

3.40 

3.90 

4.20 

3.90 

3.59 

22.66 

17.60 

.87 

.32 

.10 

1.09 

.27 

.32 

.27 

12.42 

10.35 
84.27 
84.53 
84.26 
85.24 
84.70 
40.71 
30.25 
33.83 
32.71 

34.43 

23.92 

11.65 

1.2 



Casein 

and 
albumen 



pr. ct. 

3.55 

3.50 
3.20^ 
3.512 
3.40 
17.64'' 
3.76 



3.26 



3.55 
4.03 



.86 
.81 

11.92 



Milk 
susar 



pr. ct. 
4.88 
4.60 
5.10 



4.85 
2.67 
4.23 



4.74 



5.25 
4.04 



4.79 
5.80 



Ash 



pr. 



ct. 
,71 
,75 
,70 

.71 
.75 
.56 
.53 
.62 
.70 



.80 
.72 



65 



14.49 



11.79 50.06 
1.26 
.61 



.81 

1.57 

.95 

18.84 
25.35 
23.72 
26.38 

28.00 
29.67 
34.06 
43.1 



.68 
.66 



2.18 



5.61 
.95 3. 



5.51 



1.79 
3.42 



4.73 

4.87 
5.2 



Autliority 



Konig^ 

Fleischmann 

Van Slyke 

Holland® 

Richmond 

Konig* 

Holland* 
Konig" 
Holland® 
Van Slyke 
Konig'' 
Holland® 
Konig^ 
Van Slyke 

Konig* 



WoU 
Konig' 

Woll 

FarringtoB 

Konig^ 

Van Slyke 
Drew 

Shutt 

Konig' 
(( 

Storch 



1 .70 per cent, albumen. 

* Forty-two analyses. 

• Eight analyses. 



^ 13.60 per cent, albumen. 
* Mostly European samples. 
6 Massachusetts' samples. 



260 



Testing Milk and Its Products. 



CO 

S3 

O 
u 

>> 

u 
O 

HH 

C» 
Ih 

a 

+-» 



0) 

c/3 






I.U -^ WW 

L. ^ S o 

tS fi p o 

'-"':3-- ft 

3 CB k^ 



c3 






05 





C c3 








+3 . 


s 


t/3 jj 
00 


c3 


^ s 





::2 a 


gfO 




-fci 





a^ 


ft 


v 



fe 



ft 

o 



ftn 



0^ o o ce 

?2 ^ !^ t. =« 



O 
00 



o 

00 






10 CO 



o 









H^ 



a 






ft= 



10 
10 oq L-. 

CO 00 CO CO W CO CO 



iq iq 



O iq 



o CO iq 

05 05 Ci OS 



iq 

CO 



iq 

C5 



iq 
(M CO (M c4 



fto 



iq 

CO CM OQ Cq rH 



(33 

Q 



5p 



C3 

^ TO 

O ^ 

O I— I 



go 



a PI 






Co .r-H 



-M .^' 



2 « 
•f-i "i-i 






O <D <D 






Appendix. 



261 



^c5 












oft? 



OQ 



rr^ 0) o ^ .55 



O 
CD 



CO 









cc 



C3d 



I — I to 
»o lO<^^ 



rs QO 05 



o 



(M 



r— iiO 
lO • 



c3a 
GO j: 






. c3 
73 d 

^Is 1 






lO CO 



C O t^ lO 
cc Tt< c^i CO 



o 

C5 



o c o o o o o 

Oq CO G^ (M* <M C<J (M* 



1 — lO .• iO 

"^.c^^i^i 

I — I aQ 



o 

.5 o 

e3 - 



:_ce 
: e- 

C3 






o o 

g >, 

^3 



C 03 O 






>i c3 

ci 0) 






o 

«i 
a 

8 
fa 

o 

p. 



a 

"a 

► 

« 
« 

*f a 

3 * 

bed 

<-z 

ai^ (D-d 

*J CO to u 

c c *> S 
2'S 0.'*' 

u*:>^ c 

O o o c 

»3^ 3 fc 
"^ O O c 

5>^ 






% 



1 



262 



Testing Milk and Its Products. 



Table HI. Quevenne lactometer degrees corresponding to 
N. Y. Board of Health degrees. (See par. 114) 



6d. of Health 
degrees. 



Quevenne 
■cale. 



60 


17.4 


61 


17.7 


62 


18.0 


63 


18.3 


64 


18.6 


65 


18.8 


66 


19.1 


67 


19.4 


68 


19.7 


69 


20.0 


70 


20.3 


71 


20.6 


72 


20.9 


73 


21.2 


74 


21.5 


75 


21.7 


76 


22.0 


77 


22.3 


78 


22.6 


79 


22.9 


80 


23.2 



Bd. of Health 
degrees. 



81 
82 
83 
84 
85 
86 
87 
88 
89 
90 
91 
92 
93 
94 
95 
96 
97 
98 
99 
100 



Quevenne 
scale. 



23.5 
23.8 
24.1 
24.4 
24.6 
24.9 
25.2 
25.5 
25.8 
26.1 
26.4 
26.7 
27.0 
27.3 
27.6 
27.8 
28.1 
28.4 
28.7 
29.0 



Bd. of Health 
degrees. 



101 
102 
103 
104 
105 
106 
107 
108 
109 
110 
111 
112 
113 
114 
115 
116 
117 
118 
119 
120 



Quevenne 
scale. 



29.3 
29.6 
29.9 
80.2 
80.5 
80.7 
31.0 
31.3 
81.6 
31.9 
32.2 
82.6 
82.8 
83.1 
83.4 
33.6 
33.9 
84.2 
84.5 
84.8 



Table IV. Value of 



1008—100 

B 



for sp. gr. from 1.019 to 1.0369. 



Sp.gr. (8) = 


0.0000 


0.0001 


0.0002 


0.0003 


0.0004 


0.0005 


0.0006 


0.0007 


0.0008 


O.OOOi 


1.019 


1.864 


1.874 


1.884 


1.894 


1.903 


1.913 


1.922 


1.932 


1.941 


1.951 


1.020 


1.961 


1.970 


1.980 


1.990 


1.999 


2.009 


2.018 


2.028 


2.038 


2.047 


1.021 


2.057 


2.066 


2.076 


2.086 


2.095 


2.105 


2.114 


2.124 


2.133 


2.148 


1.022 


2.153 


2.162 


2.172 


2.181 


2.191 


2.200 


2.210 


2.220 


2.229 


2.239 


1.028 


2.249 


2.258 


2.267 


2.277 


2.286 


2.296 


2.306 


2.315 


2.325 


2.334 


1.024 


2.344 


2.353 


2.363 


2.372 


2.382 


2.391 


2.401 


2.410 


2.420 


2.430 


1.025 


2.439 


2.449 


2.458 


2.468 


2.477 


2.487 


2.496 


2.506 


2.515 


2.525 


1.026 


2.534 


2.544 


2.553 


2.563 


2.573 


2.582 


2.591 


2.601 


2.610 


2.620 


1.027 


2.629 


2.638 


2.648 


2.657 


2.667 


2.676 


2.686 


2.695 


2.705 


2.714 


1.028 


2.724 


2.733 


2.743 


2.752 


2.762 


2.771 


2.781 


2.790 


2.799 


2.V09 


1.029 


2.818 


2.828 


2.837 


2.847 


2.856 


2.865 


2.875 


2.884 


2.893 


2.903 


1.030 


2.913 


2.922 


2.931 


2.941 


2.951 


2.960 


2.969 


2.979 


2.988 


2.997 


1.031 


3.007 


3.016 


3.026 


3.035 


3.044 


3.054 


3.063 


3.072 


3.082 


3.091 


1.032 


3.101 


3.110 


3.120 


3.129 


3.138 


3.148 


3.157 


3.166 


3.176 


3.185 


1.033 


3.195 


3.204 


3.213 


3.223 


3.232 


3.241 


3.251 


3.260 


3.269 


3.279 


1.034 


3.288 


3.298 


3.307 


3.316 


3.326 


3.335 


3.344 


3.354 


3.363 


3.372 


1.035 


3.382 


3.391 


3.400 


3.410 


3.419 


3.428 


3.438 


3.447 


3.456 


3.466 


1.036 


3.475 


3.484 


3.494 


3.503 


8.512 3.521 


3.531 


3.540 


3.549 


3.559 



(See direction* for use, par. 125) 



Appendix. 



263 





Table V. Correction-table for 


Specific gravity of milk. 




Temperature of milk (in degrees Fahrenheit). 






















o2 


51 


52 


53 


54 


55 


56 


57 


58 


59 


60 


20 


19.3 


19.4 


19.4 


19.5 


19.6 


19.7 


19.8 


19.9 


19.9 


20. u 


21 


20.3 


20.3 


20.4 


20.5 


20.6 


20.7 


20.8 


20.9 


20.9 


21.0 


22 


21.3 


21.3 


21.4 


21.5 


21.6 


21.7 


21.8 


21.9 


21.9 


22.0 


23 


22.3 


22.3 


22.4 


22.5 


22.6 


22.7 


22.8 


22.8 


22.9 


23.0 


24 


23.3 


23.3 


23.4 


23.5 


28.6 


23.6 


23.7 


23.8 


23.9 


24.0 


25 


24.2 


24.3 


24.4 


24.5 


24.6 


24.6 


24.7 


24.8 


24.9 


25.0 


26 


25.2 


25.2 


2-5.3 


2.5.4 


25.5 


25.6 


25.7 


25.8 


2.5.9 


26.0 


27 


26.2 


26.2 


26.3 


26.4 


26.5 


26.6 


26.7 


26.8 


26.9 


27.0 


28 


27.1 


27.2 


27.3 


27.4 


27.5 


27.6 


27.7 


27.8 


27.9 


28.0 


29 


28.1 


28.2 


28.3 


28.4 


28.5 


28.6 


28.7 


2S.8 


28.9 


29.0 


30 


29.1 


29.1 


29.2 


29.3 


29.4 


29.6 


29.7 


2i).8 


2.J.9 


30.0 


31 


30.0 


30.1 


30.2 


30.3 


30.4 


30.5 


30.6 


8,). 8 


80.9 


31.0 


32 


31.0 


31.1 


31.2 


31.3 


31.4 


31.5 


31.6 


81.7 


31.9 


32.0 


33 


31.9 


32.0 


32.1 


32.3 


32.4 


32.5 


32.6 


32.7 


82.9 


33.0 


34 


32.9 


38.0 


33.1 


33.2 


38.3 


38.5 


38.6 


33.7 


33.9 


34.0 


35 


33.8 


33.9 


34.0 


34.2 


34.3 


34.5 


34.6 


34.7 


34.9 


a5.o 




61 


62 


63 


64 


65 


66 


67 


68 


69 


70 


20 


20.1 


20.2 


20.2 


20.3 


20.4 


20.5 


20.6 


20.7 


20.9 


21.0 


21 


21.1 


21.2 


21.3 


21.4 


21.5 


21.6 


21.7 


21.8 


22.0 


22.1 


22 


22.1 


22.2 


22.3 


22.4 


22.5 


22.6 


22.7 


22.8 


28.0 


23.1 


23 


23.1 


23.2 


23.3 


23.4 


23.5 


23.6 


23.7 


23.8 


24.0 


24.1 


24 


24.1 


24.2 


24.3 


24.4 


24.5 


24.6 


24.7 


24.9 


25.0 


25.1 


25 


25.1 


25.2 


25.3 


25.4 


25.5 


25.6 


25.7 


25.9 


26.0 


26.1 


26 


26.1 


26.2 


26.3 


26.5 


26.6 


26.7 


26.8 


27.0 


27.1 


27.2 


27 


27.1 


27.3 


27.4 


27.5 


27.6 


27.7 


27.8 


28.0 


28.1 


28.2 


28 


28.1 


28.3 


28.4 


28.5 


28.6 


28.7 


28.8 


29.0 


29.1 


29.2 


29 


29.1 


29.3 


29.4 


29.5 


29.6 


29.7 


29.9 


30.1 


30.2 


30.3 


30 


30.1 


30.3 


30.4 


30.5 


30.7 


30.8 


30.9 


31.1 


31.2 


31.3 


31 


31.2 


31.3 


31.4 


31.5 


31.7 


31.8 


31.9 


32.1 


32.2 


32.4 


32 


32.2 


32.3 


32.5 


32.6 


32.7 


32.9 


33.0 


33. L 


33.3 


33.4 


33 


33.2 


33.3 


33.5 


33.6 


33.8 


33.9 


34.0 


34.2 


34.3 


34.5 


34 


34.2 


34.3 


34.5 


34.6 


34.8 


34.9 


35.0 


35.2 


35.3 


35.5 


35 


35.2 


35.3 


35.5 


35.6 


35.8 


85.9 


36.1 


36.2 


36.4 


36.5 



Directions.— Bring the temperature of the mUk to within 10° of 
60° F. Talse the reading of the lactometer and that of the temperature of 
the milk; find the former in the first vertical column of the table and the 
latter in the first horizontal row of figures; the figure where the horizontal' 
and vertical columns meet Is the corrected lactometer reading; e.g., ob- 
served, 31.0 at 67° F. ; corrected reading, SI .9. 



264 



Testing Milk and Its Products. 



fable VI. Per cent, of solids not fat, corresponding to to 
6 per cent, of fat, and lactometer readings of 26 to 

36. (See directions for use, par. 120) 



V4 

O 

h 


Lactometer readings at 60° F. 


■3 


26 


27 


28 


29 


30 


31 


32 


33 


34 


35 


36 







6.50 


6.75 


7.00 


7.25 


7.50 


7.75 


8.00 


8.25 


8.50 


8.75 


9.00 





0.1 


6.52 


6.77 


7.02 


7.27 


7.6LI/.77 


8.02 


8.27 


8.52 


8.77 


9.02 


0.1 


0.2 


6.54 


6.79 


7.04 


7.29 


7.54 


7.79 


8.04 


8.29 


8.54 


8.79 


9.04 


0.2 


0.3 


6.56 


6.81 


7.06 


7.31 


7.56 


7.81 


8.06 


8.31 


8.56 


8.81 


9.06 


0.3 


0.4 


6.58 


6.83 


7.08 


7.33 


7.58 


7.83 


8.08 


8.33 


8.58 


8.83 


9.08 


0.4 


0.5 


6.60 


6.85 


7.10 


7.35 


7.60 


7.85 


8.10 


8.35 


8.60 


8.85 


9.10 


0.5 


0.6 


6.62 


6.87 


7.12 


7.37 


7.62 


7.87 


8.12 


8.37 


8.62 


8.87 


9.12 


0.6 


0.7 


6.64 


6.89 


7.14 


7.39 


7.64 


7.89 


8.14 


8.89 


8.64 


8.89 


9.14 


0.7 


0.8 


6.66 


6.91 


7.16 


7.41 


7.66 


7.91 


8.16 


8.41 


8.66 


8.91 


9.16 


0.8 


0.9 


6.68 


6.93 


7.18 


7.43 


7.68 


7.93 


8.18 


8.43 


8.68 


8.93 


9.1^ 


0.9 


1.0 


6.70 


6.95 


7.20 


7.45 


7.70 


7.95 


8.20 


8.45 


8.70 


8.95 


9.20 


1.0 


1.1 


6.72 


6.97 


7.22 


7.47 


7.72 


7.97 


8.22 


8.47 


8.72 


8.97 


9.22 


1.1 


1.2 


6.74 


6.99 


7.24 


7.49 


7.74 


7.99 


8.24 


8.49 


8.74 


8.99 


9.24 


1.2 


1.3 


6.76 


7.01 


7.26 


7.51 


7.76 


8.01 


8.26 


8.51 


8.76 


9.01 


9.26 


1.3 


1.4 


6.78 


7.03 


7.28 


7.53 


7.78 


8.03 


8.28 


8.53 


8.78 


9.03 


9.28 


1.4 


1.5 


6.80 


7.05 


7.30 


7.55 


7.80 


8.05 


8.30 


8.55 


8.80 


9.05 


9.30 


1.5 


1.6 


6.82 


7.07 


7.32 


7.57 


7.82 


8.07 


8.32 


8.57 


8.82 


9.07 


9.32 


1.0 


1.7 


6.84 


7.09 


7.34 


7.59 


7.84 


8.09 


8.34 


8.59 


8.84 


9.09 


9.34 


1.7 


1.8 


6.86 


7.11 


7.36 


7.61 


7.86 


8.11 


8.36 


8.61 


8.86 


9.11 


9.37 


1.8 


1.9 


6.88 


7.13 


7.38 


7.63 


7.88 


8.13 


8.38 


8.63 


8.88 


9.13 


9.39 


1.9 


2.0 


6.90 


7.15 


7.40 


7.65 


7.90 


8.15 


8.40 


8.66 


8.91 


9.16 


9.41 


2.0 


2.1 


6.92 


7.17 


7.42 


7.67 


7.92 


8.17 


8.42 


8.68 


8.93 


9.18 


9.43 


2.1 


2.2 


6.94 


7.19 


7.44 


7.69 


7.94 


8.19 


8.44 


8.70 


8.95 


9.20 


9.45 


2.2 


2.3 


6.96 


7.21 


7.46 


7.71 


7.96 


8.21 


SM 


8.72 


8.97 


9.22 


9.47 


2.3 


2.4 


6.98 


7.23 


7.48 


7.73 


7.98 


8.23 


8.48 


8.74 


8.99 


9.24 


9.49 


2.4 


2.5 


7.00 


7.25 


7.50 


7.75 


8.00 


8.25 


8.50 


8.76 


9.01 


9.26 


9.51 


2.6 


2.6 


7.02 


7.27 


7.52 


7.77 


8.02 


S.27 


8.52 


8.78 


9.03 


9.28 


9.53 


2.6 


2.7 


7.04 


7.29 


7.54 


7.79 


8.04 


^.29 


8.54 


8.80 


9.05 


9.30 


9.55 


2.7 


2.8 


7.06 


7.31 


7.56 


7.81 


8.06 


8.31 


8.57 


8.82 


9.07 


9.32 


9.57 


2.8 


2.9 


7.08 


7.33 


7.58 


7.83 


8.08 


8.33 


8.59 


3.84 


9.09 


9.34 


9.59 


2.9 



Appendix. 



265 



Table VI. Per cent, of solids not fat {Continued). 



•j 

s- 


Lactometer Readings at 60° F. 


flu 




26 


27 


28 


29 


30 


31 


32 
8.61 


33 


34 


35 


36 


fl) o 


3.0 


7.10 


7.35 


7.60 


7.85 


8.10 


8.36 


8.86 


9.11 


9.3G 


9.61 


3.0 


3.1 


7.12 


7.37 


7.62 


7.87 


8.13 


8.38 


8.63 


8.88 


9.13 


9.38 


9.64 


3.1 


3.2 


7.14 


7.3!' 


7.64 


7.89 


8.15 


8.40 


8.65 


8.90 


9.15 


9.41 


9.66 


3.2 


3.3 


7.16 


7.41 


7.66 


7.92 


8.17 


8.42 


8.67 


8.92 


9.18 


9.43 


9.68 


3.3 


3.4 


7.18 


7.43 


7.69 


7.94 


8.19 


8.44 


8.69 


8.94 


9.20 


9.45 


9.70 


3.4 


3.5 


7.20 


7.45 


7.71 


7.96 


8.21 


8.46 


8.71 


8.96 


9.22 


9.47 


9.72 


3.5 


3.6 


7.22 


7.48 


7.73 


7.98 


8.23 


8.48 


8.73 


8.98 


9.24 


9.49 


9.74 


3.6 


3.7 


7.24 


7.50 


7.75 


8.00 


8.25 


8.50 


8.75 


9.00 


9.26 


9.51 


9.76 


3.7 


3.8 


7.26 


7.52 


7.77 


8.02 


8.27 


8.52 


8.77 


9.02 


9.28 


9.53 


9.78 


3.8 


3.9 


7.28 


7.54 


l.To 


8.04 


8.29 


8.54 


8.79 


9.04 


9.30 


9.55 


9.80 


3.9 


4.0 


7.30 


7.56 


7.81 


8.06 


8.31 


8.50 


8.81 


9.06 


9.32 


9.57 


9.83 


4.0 


4.1 


7.32 


7.58 


7.83 


8.08 


8.33 


8.58 


8.83 


9.08 


9.34 


9.59 


9.85 


4.1 


4.2 


7.34 


7.60 


7.85 


8.10 


8.35 


8.60 


8.85 


9.11 


9.30 


9.62 


9.87 


4.2 


4.3 


7.86 


7.62 


7.87 


8.12 


8.37 


8.62 


8.88 


9.13 


9.38 


9.64 


9.89 


4.3 


4.4 


7.38 


7.64 


7.89 


8.14 


8.39 


8.64 


8.90 


9.15 


9.40 


9.66 


9.91 


4.4 


4.5 


7.40 


7.66 


7.91 


8.16 


8.41 


8.66 


8.92 


9.17 


9.42 


9.08 


9.93 


4.5 


4.6 


7.43 


7.68 


7.93 


8.18 


8.43 


8.68 


8.94 


9.19 


9.44 


9.70 


9.95 


4.6 


4.7 


7.45 


7.70 


7.95 


8.20 


8.4.5 


8.70 


8.96 


9.21 


9.46 


9.72 


9.97 


4.7 


4.8 


7.47 


7.72 


7.97 


8.22 


8.47 


8.72 


8.98 


9.23 


9.48 


9.74 


9.99 


4.8 


4.9 


7.49 


7.74 


7.99 


8.24 


8.49 


8.74 


9.00 


9.25 


9.50 


9.76 


10.01 


4.9 


5.0 


7.51 


7.76 


8.01 


8.26 


8.51 


8.76 


9.02 


9.27 


9.52 


9.78 


10.03 


5.0 


5.1 


7.53 


7.78 


8.03 


8.28 


8.53 


8.79 


9.04 


9.29 


9.54 


9.80 


10.05 


5.1 


5.2 


7.55 


7.80 


8.05 


8.30 


8.55 


8.81 


9.06 


9.31 


9.56 


9.82 


10.07 


5.2 


5.3 


7.57 


7.82 


8.07 


8.32 


8.57 


8.83 


9.08 


9.33 


9.58 


9.84 


10.09 


5.3 


5.4 


7.59 


7.84 


8.09 


8.34 


8.60 


8.85 


9.10 


9.36 


9.61 


9.86 


10.11 


5.4 


5.6 


7.61 


7.86 


a.ll 


8.36 


8.62 


8.87 


9.12 


9.38 


9.63 


9.88 


10.13 


5.5 


6.6 


7.63 


7.88 


8.13 


3.39 


8.64 


8.89 


9.15 


9.40 


9.65 


9.90 


10.15 


5.6 


6.7 


7.65 


7.90 


8.15 


3.41 


8.66 


8.91 


9.17 


9.42 


9.67 


9.92 


10.17 


5.7 


5.8 


7.67 


7.92 


B.17I 


3.43 


8.68 


8.94 


9.19 


9.44 


9.69 


9.94 


10.19 


5.8 


5.9 


7.69 


7.94 


3.20 J 


3.45 


3.70 


3.96 


9.21 


9.46 


9.71 


9.96 


10.22 


5.9 


6.0 ' 


7.71 


7.96! 


3.22! 


3.47! 


3.72! 


3.98 < 


).23l 


3.48 < 


3.73 


9.98 


10.24 


6.0 



266 Testing Milk and Its Products. 

Directions for Use of Tables VII, VIII, IX, and XI. 

TABLES VII, and VIII. Find the test of the milk in table VII ot 
of cream in table VIII; the first or last horizontal row of fig- 
ures, the amounts of fat in ten thousand, thousands, hundreds, 
tens, and units of pounds of milk are then given in this verti- 
cal column. By adding the corresponding figures for any given 
quantity of milk or of cream, the total quantity of butter fat 
contained therein is obtained. 

Example: How many pounds of fat Is contained In 8925 lbs. of milk 
testing 3.bo per cent.? On p 264, -econd column the test 3.65 is found, and 
by going downward in this cu.uinu we have: 

8000 lbs 292. lbs. 

QUO lbs 32.9 lbs. 

20 lbs .7 lbs. 

6 lbs 2 lbs. 

8925 lbs. of milk. 325.8 lbs. of fat. 

8925 lbs. of milk testing 3.65 per cent., therefore, contains 825.8 lbs. of 
butter fat. 

TABLC IX. The price per pound is given in the outside vertical 

columns, and the weight of butter fat in the upper and lower 

horizontal row of figures. The corresponding tens of pounds 

are found by moving the decimal point one place to the left, 

the units, by moving it two, and the tenths of a pound, by 

moving it three places to the left. The use of the table is, 

otherwise, as explained abovfe. 

Example: How much money is due for 325.8 lbs. of butter fat at 15>^ 
cents per pound? In the horizontal row of figures beginning with 15>i on 
p. 247, we find t 

800 lbs 846.50 

20 lbs 3.10 

6 lbs 77 

.8 lbs 12 

325.8 lbs. S50.49 

826.8 lbs. of butter fat at 1534 cents per pound, therefore, Is worth $50.49. 

TABLE XI. Find the test of milk in the upper or lower hori- 
zontal row of figures. The amounts of butter likely to be made 
from ten thousand, thousands, hundreds, tens, and units of 
pounds of milk are tlien given in this vertical column. The use 
of the table is, otherwise, as explained above in case of table VII. 

Example: How much butter will 5845 lbs. of milk testing 3.8 per cent, 
be apt to make under good creamery conditions? In the column headed 
3.8* we find : 

6000 lbs 209.0 lbs. 

800 lbs 33.4 lbs. 

40 lbs 1.7 lbs. 

6 lbs 2 lbs. 

6845 lbs. 244.3 lbs. 

5845 lbs. of milk test ng 3.8 per cent, of fat will make about 244.3 lb«. of 
butter, under oondi Lions similar to those explained in par. 220. 



Appendix. 



267 



Table Vil. Pounds of fat in I to 10,000 lbs. of milk, testing 3.0 
to 5.35 per cent. (See directions for use, p. 266 ) 





3.00 


3.05 


3.10 


3.15 


3.20 


3.25 


3.30 


3.35 


3.40 3.45 


3.50 


3.55 




Milk 


























Milk 


lbs. 


























lbs. 


10,000 


300 


305 


310 


315 


320 


325 


330 


335 


340 


345 


350 


355 


10,000 


9,000 


270 


275 


270 


284 


289 


293 


297 


302 


306 


311 


315 


320 


9,000 


8,000 


240 


244 


248 


252 


256 


260 


264 


268 


272 


276 


280 


284 


8,000 


7,000 


210 


214 


217 


221 


224 


228 


231 


235 


238 


242 


245 


249 


7,000 


6,000 


180 


183 


186 


189 


102 


11)5 


19.S 


201 


204 


207 


210 


213 


6,000 


5,000 


150 


153 


155 


158 


160 


163 


165 


168 


170 


173 


175 


178 


5,000 


4,000 


120 


122 


124 


126 


128 


130 


132 


134 


136 


138 


140 


142 


4,000 


3,000 


90.0 


91.5 


93.0 


94.5 


96.0 


97.5 


99.0 


101 


102 


104 


105 


107 


3,000 


2,000 


GO.O 


61.0 


62.0 


63.0 


64.0 


65.0 


66.0 


'w.O 


68.0 


60.0 


70.0 


71.0 


2,000 


1,000 


30.0 


30.5 


31.0 


31.5 


32.0 


32.5 


33.0 


33.5 


34.0 


34.5 


35.0 


35.5 


1,000 


900 


27.0 


27.5 


27.9 


28.4 


28.8 


29.3 


29.7 


30.2 


30.6 


31.1 


31.5 


32.0 


900 


800 


24.0 


24.4 


24.8 


25.2 


25.7 


26.0 


26.4 


26.8 


27.2 


27.6 


28.0 


28.4 


800 


700 


21.0 


21.! 


21.7 


22.1 


22.4 


22.8 


23.1 


23.5 


23.8 


24 2 


24.5 


24.9 


700 


600 


18.0 


18.3 


18.6 


18.9 


19.2 


19.5 


19.8 


20.1 


20.4 


20^7 


21.0 


21.3 


600 


500 


15.0 


15.3 


15.5 


15.8 


V'kO 


16.3 


16.5 


16.8 


17.0 


17.3 


17.5 


17.8 


500 


400 


12.0 


12.2 


12.4 


12.6 


12.8 


13.0 


13.2 


13.4 


13.6 


13.8 


14.0 


14.2 


400 


300 


9.0 


9.2 


9.3 


9.5 


9.6 


9.8 


9.9 


10.1 


10.2 


10.4 


10.5 


10.7 


300 


200 


G.O 


6.1 


6.2 


6.3 


6.4 


6.5 


6.6 


6.7 


6.8 


0.9 


7.0 


7.1 


200 


100 


3.0 


3.1 


3.1 


3.2 


3.2 


3.3 


3.3 


3.4 


3.4 


3.5 


3.5 


3.6 


100 


90 


2.7 


2.8 


2.8 


2.8 


2.9 


2.9 


3.0 


3.0 


3.1 


3.1 


3.2 


3.2 


90 


80 


2.4 


2-. 4 


2.5 


2.5 


2.G 


2.6 


2.6 


2.7 


2.7 


2.8 


2.8 


2.8 


80 


70 


2.] 


2.1 


2.2 


2.2 


2 2 


2.3 


2.3 


2.3 


2.4 


2.4 


2.5 


2.5 


70 


60 


1.8 


1.8 


1.9 


1.9 


l!9 


2.0 


2.0 


2.0 


2.0 


2.1 


2.1 


2.1 


60 


50 


1.5 


1.5 


1.6 


'1.6 


1.6 


1.6 


1.7 


1.7 


1.7 


1.7 


1.8 


1.8 


50 


40 


1.2 


1.2 


1.2 


1.3 


1.3 


1.3 


1.3 


1.3 


1.4 


1.4 


1.4 


1.4 


40 


30 


.9 


.9 


.9 


.9 


1.0 


1.0 


1.0 


1.0 


1.0 


1.0 


1.1 


1.1 


30 


20 


.6 


.6 


.6 


.6 


.6 


.7 


.7 


.7 


.7 


.7 


.7 


.7 


20 


10 


.3 


.3 


.31 .3 


.3 


.3 


.3 


.3 


.3 


.3 


.4 


.4 


10 


9 


.3 


.3 


.3 


.3 


.3 


.3 


.3 


.3 


.3 


.3 


.3 


.3 


9 


8 


.2 


.2 


.2 


.3 


.3 


.3 


.3 


.3 


.3 


.3 


.3 


.3 


8 


7 


.2 


2 


.2 


.2 


.2 


.2 


.2 


.2 


.2 


.2 


.2 


.2 


7 


6 


.2 


.*2 


.2 


.2 


.2 


.2 


.2 


.2 


.2 


.2 


.2 


.2 


6 


5 


.2 


.2 


.2 


'.2 


.2 


.2 


.2 


o 


.2 


.2 


.2 


.2 


5 


4 


.1 


.1 


.1 


.1 


.1 


.1 


.1 


A 


.1 


.1 


.1 


.1 


4 


3 


.1 


.1 


.1 


.1 


.1 


.1 


.1 


.1 


.1 


.1 


.1 


.1 


3 


2 

1 


.1 


.1 


.1 


.1 


.1 


1 


.1 


.1 


.1 


.1 


.1 


.1 


2 

1 




3.00 


3.05 


3.10 


3.15 


3.20 


3.25 


3.30 


3.35 


3.40 


3.45 


3.50 


3.55 





268 



Testing Milk and Its Products. 



Table V( 


1. Pounds of fat in 


1 to 10,000 lbs 


. of milk 


[ Continue 


d). 


00 


3.60 


3.65 


3.70 


3.75 


3.80 


3.85 


3.90 


3.95 


4.00 


4.05 


4.10 


4.15 




A! ilk 
lbs. 
























Milk 
lbs. 


10,000 


360 


365 


370 


375 


380 


385 


390 


395 


400 


405 


410 


415 


10,000 


9,000 


324 


329 


333 


338 


342 


347 


351 


356 


360 


3(55 


369 


374 


9,000 


8,000 


288 


292 


296 


300 


304 


308 


312 


316 


320 


324 


328 


332 


8,000 


7.000 


252 


256 


259 


263 


266 


■270 


273 


277 


280 


284 


287 


291 


7,000 


6,000 


216 


219 


222 


225 


228 


231 


234 


237 


240 


243 


246 


249 


6,000 


5,000 


180 


183 


185 


188 


190 


193 


195 


198 


200 


203 


205 


208 


5,000 


4,000 


144 


146 


148 


150 


lo2 


154 


156 


158 


160 


162 


164 


166 


4,000 


3,000 


108 


110 


111 


113 


114 


116 


117 


119 


120 


122 


123 


125 


3,000 


2,000 


72.0 


73.0 


74.0 


75.0 


76.0 


77.0 


78.0 


79.0 


80.0 


81.0 


82.0 


83.0 


2,000 


1,000 


36.0 


36.5 


37.0 


37.5 


38.0 


38.5 


39.0 


39.5 


40.0 


40.5 


41.0 


41.5 


1,000 


900 


32.4 


32.9 


33.3 


33.8 


34.2 


34.7 


35.1 


35.6 


36.0 


36.5 


36.9 


37.4 


900 


800 


28.8 


29.2 


29.6 


30.0 


30.4 


30.8 


31.2 


31.6 


32.0 


.32.4 


3'2.8 


33.2 


800 


700 


25.2 


25.6 


25.9 


26.3 


26.6 


27.0 


27.3 


27.7 


28.0 


28.4 


28.7 


29.1 


700 


600 


21.6 


21.9 


22.2 


22.5 


22.8 


23.1 


23.4 


23.7 


24.0 


24.3 


24.6 


24.9 


600 


500 


18.0 


18.3 


18.5 


18.8 


19.0 


19.3 


19.5 


19.8 


20.0 


20.3 


20.5 


20.8 


500 


400 


14.4 


14.6 


14.8 


15.0 


15.2 


15.4 


15.6 


15.8 


16.0 


16.2 


16.4 


16.6 


400 


300 


10.8 


11.0 


11.1 


11.3 


11.4 


11.6 


11.7 


11.9 


12.0 


12.2 


12.3 


12.5 


300 


200 


7.2 


7.3 


7.4 


7.5 


7.6 


7.7 


7.8 


7.9 


8.0 


8.1 


8.2 


8.3 


200 


100 


3.6 


3.7 


3.7 


3.8 


3.8 


3.9 


3.9 


4.0 


4.0 


4.1 


4.1 


4.2 


100 


90 


3.2 


3.3 


3.3 


3.4 


3.4 


3.5 


3.5 


3.6 


3.6 


3.7 


3.7 


3.7 


90 


80 


2.9 


2.9 


3.0 


3.0 


3.0 


3.1 


3.1 


3.2 


3.2 


3.2 


3.3 


3.3 


80 


70 


2.5 


2.6 


2.6 


2.6 


2.7 


2.7 


2.7 


2.8 


2.8 


2.8 


2.9 


2.9 


70 


60 


2.2 


2.2 


2.2 


2.3 


2.3 


2.3 


2.3 


2.4 


2.4 


2.4 


2.5 


2.5 


60 


50 


1.8 


1.8 


1.9 


1.9 


1.9 


1.9 


2.0 


2.0 


2.0 


2.0 


2.1 


2.1 


50 


40 


1.4 


1.5 


1.5 


1.5 


1.5 


1.5 


1.6 


1.6 


1.6 


1.6 


1.6 


1.7 


40 


30 


1.1 


1.1 


1.1 


1.1 


1.1 


1.2 


1.2 


1.2 


1 2 


1.2 


1.2 


1.2 


30 


20 


.7 


.7 


.7 


.8 


.8 


.8 


.8 


.8 


.8 


.8 


.8 


.8 


20 


10 


.4 


.4 


.4 


.4 


.4 


.4 


.4 


.4 


.4 


.4 


.4 


.4 


10 


9 


.3 


.3 


.3 


.3 


.3 


.3 


.4 


.4 


.4 


.4 


.4 


.4 


9 


8 


.3 


.3 


.3 


.3 


.3 


.3 


.3 


.3 


.3 


.3 


.3 


.3 


8 


7 


.3 


.3 


.3 


.3 


.3 


.3 


.3 


.3 


.3 


.3 


.3 


.3 


7 


3 


.2 


.2 


.2 


.2 


.2 


.2 


.2 


.2 


.2 


.2 


.2 


.2 


6 


5 


.2 


.2 


.2 


.2 


.2 


._ 


.2 


.2 


.2 


.2 


.2 


.2 


5 


4 


.1 


.1 


.1 


.2 


.2 


2 


.2 


.2 


.2 


.2 


.2 


.2 


4 


^ 


.1 


.1 


.1 


.1 


.1 


.1 


.1 


.1 


.1 


.1 


.1 


.1 


8 


2 

1 


.1 


.1 


.1 


.1 


.1 


.1 


.1 


.1 


.1 


.1 


.1 


.1 


2 
1 


1 


3.60 


3.65 


3.70 


3.75 


3.80 


3.85 


3.90 


3.95 


4.00 


4.05 


4.10 


4.15 


§ 

^ 



Appendix. 



269 



Table VII. Pounds of fat in 


1 to 10,000 lbs 


. of milk 


[Continued). 


-1^ 

00 

H 


4.20 


4.25 


4.30 


4.35 


4.40 


4.45 


4.50 


4.55 


4.60 


4.65 


4.70 


4.75 




Milk 


























Milk 


lbs. 


























lbs. 


10,000 


420 


42.5 


430 


435 


440 


445 


450 


455 


460 


465 


470 


475 


10,000 


9,000 


378 


383 


387 


392 


396 


401 


405 


410 


414 


419 


423 


428 


9,000 


8,000 


336 


340 


344 


348 


352 


356 


360 


364 


368 


372 


376 


380 


8,000 


7,000 


294 


298 


301 


305 


308 


312 


315 


319 


322 


326 


329 


383 


7,000 


6,000 


252 


2,55 


258 


261 


264 


267 


270 


273 


276 


279 


282 


285 


6,000 


5,000 


210 


213 


215 


218 


220 


223 


225 


228 


230 


233 


235 


238 


5,0(0 


4,000 


168 


170 


172 


174 


176 


178 


180 


182 


184 


186 


188 


190 


4,000 


3,000 


126 


128 


129 


131 


132 


134 


135 


137 


138 


140 


141 


143 


3,000 


2,000 


84.0 


85.0 


86.0 


87.0 


88.0 


89.0 


90.0 


91.0 


92.0 


93.0 


94.0 


95.0 


2,000 


1,000 


42.0 


42.5 


43.0 


43.5 


44.0 


44.5 


45.0 


45.5 


46.0 


46.5 


47.0 


47.5 


1,000 


900 


37.8 


38.3 


38.7 


39.2 


89.6 


40.1 


40.5 


41.0 


41.4 


41.9 


42.3 


42.8 


900 


800 


33.6 


34.0 


34.4 


34.8 


85.2 


35.6 


36.0 


36.4 


36.8 


37.2 


37.6 


88.0 


800 


700 


29.4 


29.8 


m.i 


30.5 


80.8 


31.2 


31.5 


31.9 


32.2 


32.6 


32.9 


33.3 


700 


600 


25.2 


25.5 


'5.8 


26.1 


26.4 


26.7 


27.0 


27.3 


27.6 


27.9 


28.2 


28.5 


600 


600 


21.0 


21.3 


21.5 


21.8 


22.0 


22.3 


22.5 


22.8 


23.0 


23.3 


23.5 


23.8 


500 


400 


16.8 


17.0 


17.2 


17.4 


17.6 


17.8 


18.0 


18.2 


18.4 


18.6 


18.8 


19.0 


400 


300 


12.6 


12.8 


12.9 


13.1 


18.2 


13.4 


13.5 


13.7 


13.8 


14.0 


14.1 


14.3 


300 


200 


8.4 


8.5 


8.6 


8.7 


8.8 


8.9 


9.0 


9.1 


9.2 


9.3 


9.4 


9.5 


200 


100 


4.2 


4.3 


4.3 


4.4 


4.4 


4.5 


4.5 


4.6 


4.6 


4.7 


4.7 


4.8 


100 


90 


3.8 


3.8 


3.9 


3.9 


4.0 


4.0 


4.1 


4.1 


4.1 


4.2 


4.2 


4.3 


90 


80 


3.4 


3.4 


3.4 


3.5 


3.5 


3.6 


3.6 


3.6 


3.7 


3.7 


3.8 


3.8 


80 


70 


2.9 


3.0 


3.0 


3.0 


3.1 


8.1 


3.2 


3.2 


3.2 


3.3 


3.3 


3.3 


70 


60 


2.5 


2.6 


2.6 


2.6 


2.6 


2.7 


2.7 


2.7 


2.8 


2.8 


2.8 


2.9 


60 


50 


2.1 


2.1 


2.2 


2.2 


2.2 


2.2 


2.3 


2.3 


2.3 


2.3 


2.4 


2.4 


50 


40 


1.7 


1.7 


1^7 


1.7 


1.8 


1.8 


1.8 


1.8 


1.8 


1.9 


1.9 


1.9 


40 


30 


1.3 


1.3 


1.3 


1.3 


1.3 


1.3 


1.4 


1.4 


1.4 


1.4 


1.4 


1.4 


30 


20 


.8 


.9 


.9 


.9 


.9 


.9 


.9 


.9 


.9 


.9 


.9 


1.0 


20 


10 


.4 


.4 


.4 


.4 


.4 


.4 


.5 


.5 


.5 


.5 


.5 


.5 


10 


9 


.4 


.4 


.4 


.4 


.4 


.4 


.4 


.4 


.4 


.4 


.4 


.4 


9 


8 


.3 


.3 


.3 


.3 


.4 


.4 


.4 


.4 


.4 


,4 


.4 


.4 


8 


7 


.3 


.3 


.3 


.3 


.3 


.3 


.3 


.3 


.3 


.3 


.3 


.3 


7 


6 


.3 


.3 


.3 


.3 


.3 


.3 


. o 


.3 


.3 


.3 


.3 


.3 


6 


5 


.2 


.2 


.2 


.2 


.2 


.2 


.2 


.2 


.2 


.2 


.2 


.2 


5 


4 


.2 


.2 


.2 


.2 


.2 


.2 


2 


.2 


.2 


.2 


.2 


.2 


4 


3 


.1 


.1 


.1 


.1 


.1 


.1 


.'l 


.1 


.1 


.1 


.1 


.1 


3 


2 
1 


.1 


.1 


.1 


.1 


.1 


.1 


.1 


.1 


.1 


.1 


.1 


.1 


2 
1 












4.40 


4.45 


















4.20 


4.25 


4.30 


4.35 


4.50 


4.55 


4.60 


4.65 


4.70 


4.75 




H 


























r* 



270 



Testing Milk and Its Products. 



Table Vii. Pounds of fat in 


1 to 10.000 lbs 


►. of milk ( Continued). 




4.80 


4.85 


4.90 


4.95 


5.00 


5.05 


5.10 


5.15 


5.20 


5.25 


5.30 


5.35 


r 


Milk 


























Milk 


lbs. 


























lbs. 


10,000 


480 


485 


490 


495 


500 


505 


510 


515 


520 


525 


530 


535 


10,000 


9,000 


432 


437 


441 


446 


450 


455 


459 


464 


468 


473 


477 


482 


9,000 


8,000 


384 


388 


392 


3i)6 


400 


404 


408 


412 


416 


420 


424 


428 


8,000 


7,000 


336 


340 


343 


347 


350 


354 


357 


361 


364 


368 


371 


375 


7,000 


6,000 


288 


291 


294 


297 


300 


303 


306 


309 


312 


315 


318 


321 


6,000 


5,000 


240 


243 


245 


248 


250 


253 


255 


258 


260 


263 


265 


268 


5,000 


4,000 


192 


194 


196 


198 


200 


202 


204 


206 


208 


210 


212 


214 


4,000 


3,000 


144 


146 


147 


149 


150 


152 


153 


155 


156 


158 


159 


161 


3,000 


2,000 


96.0 


97.0 


98.0 


99.0 


100 


101 


102 


103 


104 


105 


106 


107 


2,000 


i,000 


48.0 


48.5 


49.0 


49.5 


50.0 


50.5 


51.0 


51.5 


52.0 


52.5 


53.0 


53.5 


1,000 


900 


43.2 


43.7 


44.1 


44.6 


45.0 


45.5 


45.7 


46.4 


46.8 


47.3 


47.7 


48.2 


900 


800 


38.4 


38.8 


39.2 


39.6 


40.0 


40.4 


40.8 


41.2 


41.6 


42.0 


42.4 


42.8 


800 


700 


33.6 


34.0 


34.3 


34.7 


35.0 


35.4 


35.7 


36.1 


36.4 


36.8 


37.1 


37.5 


700 


600 


28.8 


29.1 


29.4 


29.7 


30.0 


30.3 


30.6 


30.9 


31.2 


31.5 


31.8 


32.1 


600 


500 


24.0 


24.3 


24.5 


24.8 


25.0 


25.3 


25.5 


25.8 


26.0 


26.3 


26.5 


26.8 


500 


400 


19.2 


19.4 


19.6 


19.8 


20.0 


20.2 


20.4 


20.6 


20.8 


21.0 


21.2 


21.4 


400 


300 


14.4 


14.6 


14.7 


14.9 


15.0 


15.2 


15.3 


15.5 


15.6 


15.8 


15.9 


16.1 


300 


200 


9.6 


9.7 


9.8 


9.9 


10.0 


10.1 


10.2 


10.3 


10.4 


10.5 


10.6 


10.7 


200 


100 


4.8 


4.9 


4.9 


5.0 


5.0 


5.1 


5.1 


5.2 


5.2 


5.3 


5.3 


5.4 


100 


90 


4.3 


4.4 


4.4 


4.5 


4.5 


4.5 


4.6 


4.6 


4.7 


4.7 


4.8 


4.8 


90 


80 


3.8 


3.9 


3.9 


4.0 


4.0 


4.0 


4.1 


4.1 


4.2 


4.2 


4.2 


4.3 


80 


70 


3.4 


3.4 


3.4 


3.5 


3.5 


3.5 


3.6 


3.6 


3.6 


3.7 


3.7 


3.7 


70 


60 


2.9 


2.9 


2.9 


3.0 


3.0 


3.0 


3.1 


3.1 


3.1 


3.2 


3.2 


3.2 


60 


50 


2.4 


2.4 


2.5 


2.5 


2.5 


2.5 


2.6 


2.6 


2.6 


2.6 


2.7 


2.7 


50 


40 


1.9 


1.9 


2.0 


2.0 


2.0 


2.0 


2.0 


2.1 


2.1 


2.1 


2.1 


2.1 


40 


30 


1.4 


1.5 


1.5 


1.5 


1.5 


1.5 


1.5 


1.5 


1.6 


1.6 


1.6 


1.6 


30 


20 


1.0 


1.0 


1.0 


1.0 


1.0 


1.0 


1.0 


1.0 


1.0 


1.1 


1.1 


1.1 


20 


10 


.5 


.5 


.5 


.6 


.5 


.5 


.5 


.5 


.5 


.5 


.5 


.5 


10 


9 


.4 


.4 


.4 


.4 


.5 


.5 


.5 


.5 


.5 


.5 


.5 


.5 


9 


8 


.4 


.4 


.4 


.4 


.4 


.4 


.4 


.4 


.4 


.4 


.4 


.4 


8 


7 


.3 


.3 


.3 


.3 


.4 


.4 


.4 


.4 


.4 


.4 


.4 


.4 


7 


6 


.3 


.3 


.3 


.3 


.3 


.3 


.3 


.3 


.3 


.3 


.3 


.3 


6 


5 


.2 


.2 


.2 


.2 


.3 


.3 


.3 


.3 


.3 


.3 


.3 


.3 


5 


4 


.2 


.2 


.2 


.2 


.2 


.2 


.2 


.2 


.2 


.2 


.2 


.2 


4 


3 


.1 


.1 


.1 


.1 


.2 


.2 


.2 


.2 


.2 


.2 


.2 


.2 


3 


2 


.1 


.1 


.1 


.1 


.1 


.1 


.1 


.1 


.1 


.1 


.1 


.1 


2 


1 










.1 


.1 


.1 


.1 


.1 


.1 


.1 


.1 


1 














i 


4.80 


4.85 


4.90 


4.95 


5.00 


5.05 


5.10 


5.15 


5.20 


5.25 


5.30 


5.35 


? 

r 



Appendix. 



271 



Tdbfe VIII. Pounds of fat in I to 1000 lbs. of cream testing 
12.0 to 50.0 per cent. fat. 















(See direct 


ons 


fori 


ase, 


p. 266.) 














1 


12 


13 


14 


15 


16 


17 


18 


19 


20 


21 


22 


23 


24 


25 


26 


27 


28 


29 


30 










































1000 


120 


180 


140 


150 


160 


170 


180 


190 


200 


210 


220 


230 


240 


2.50 


260 


270 


280 


290 


300 


»00 


108 


117 


1J6 


135 


144 


153 


162 


171 


180 


18H 


198 


207 


216 


225 


2^4 


243 


252 


261 


270 


800 


96 


104 


112 


120 


128 


136 


144 


152 


160 


168 


176 


184 


192 


200 


208 


216 


224 


2;S2 


240 


700 


84 


91 


98 


105 


112 


119 


126 


133 


110 


147 


154 


161 


168 


175 


182 


189 


196 


203 


210 


600 


72 


78 


84 


90 


96 


102 


108 


114 


120 


126 


132 


188 


144 


150 


156 


162 


168 


174 


180 


600 


60 


65 


70 


75 


80 


85 


90 


95 


100 


105 


110 


115 


120 


125 


130 


135 


140 


145 


150 


400 


48 


62 


56 


60 


64 


68 


72 


76 


80 


84 


88 


92 


96 


100 


104 


108 


112 


116 


120 


800 


86 


39 


42 


45 


48 


61 


54 


57 


60 


63 


66 


69 


72 


76 


78 


81 


84 


87 


90 


200 


24 


26 


28 


80 


82 


34 


36 


38 


40 


42 


44 


46 


48 


60 


52 


64 


6(i 


58 


60 


100 


12 


13 


14 


16 


16 


17 


18 


19 


20 


21 


22 


23 


24 


25 


26 


27 


28 


29 


30 


90 


10.8 


11.7 


12.6 


13.5 


14.4 


15.3 


16.2 


17.1 


18.0 


18.9 


19.8 


20.7 


21.6 


22.5 


28.4 


24.3 


25.2 


26.1 


27.0 


80 


9.6 


10.4 


11.2 


12.0 


12.8 


13.6 


14.4 


15.2 


16.016.8 


17.6 


18.4 


19.2 


20.0 


20.8 


21.6 


•J2.4 


23.2 


24.0 


70 


8.4 


9.1 


9.8 


10.5 


11.2 


11.9 


12.6 


13.8 


14.0 14.7 


15.4 


16.1 


16.8 


17.5 


18.2 


18.9 


19.6 


20..3 


21.0 


00 


7.2 


7.8 


8.4 


9.0 


9.6 


10.2 


10.8 


11.4 


12.0 12.6 13.2 


13.8 


14.4 


15.0 


15.6 


16.2 


16.8 


17.4 


18.0 


60 


6.0 


6.5 


7.0 


7.5 


8.0 


8.5 


9.0 


9.5 


10.0 


10.5 


11.0 


11.5 


12.0 


12.5 


13.0 


13.5 


14.0 


14.5 


15.0 


40 


4.8 


5.2 


5.6 


6.0 


6.4 


6.8 


7.2 


7.6 


8.0 


8.4 


8.8 


9.2 


9.6 


10.0 


10.4 


10.8 


11.2 


11.6 


12.0 


80 


3.6 


3.9 


4.2 


4.5 


4.8 


5.1 


6.4 


6.7 


6.0 


6.3 


6.6 


6.9 


7.2 


7.5 


7.8 


8.1 


8.4 


8.7 


9.0 


20 


2.4 


2.6 


2,8 


3.0 


3.2 


3.4 


3.6 


3.8 


4.0 


4.2 


4.4 


4.6 


4.8 


6.0 


5.2 


6.4 


6.6 


5.8 


6.0 


10 


1.2 


l^ 


1.4 


1.6 


1.6 


1.7 


1.8 


1.9 


2.0 


2.1 


2.2 


2.3 


2.4 


2.5 


2.6 


2.7 


2.8 


2.9 


3.0 


9 


1J)8 


1.17 


1.26 


1.S5 


1.44 


1..53 


1.62 


1.71 


1.80 


1.89 


1.98 


2.07 


2.16 


2.25 


2.34 


1.43 


2.52 


2.61 


2.70 


8 


.96 


1.04 


1.12 


1.20 


1.28 


1.36 


1.44 


1 .52 


1.60 


1.68 


1.76 


1.84 


1.92 


2.00 


2.(18 


2.16 


2.24 


2.32 


2.40 


7 


.84 


.91 


.9.S 


1.05 


1.12 


1.19 


1.26 


1.33 


1.40 


1.47 


1.54 


1.61 


1.^8 


1.75 


1.82 


1.89 


1.96 


2.03 


2.10 


6 


.72 


.78 


.84 


.no 


.9t> 


1.02 


1.08 


1.14 


1.20 


1.26 


1.32 


1.38 


1.44 


1.50 


1.56 


1.62 


1.68 


1.74 


1.80 


5 


.60 


.65 


.70 


.75 


.80 


.85 


.90 


.95 


1.00 


1.05 


1.10 


1.15 


1.20 


1.25 


1.30 


1 .35 


1.40 


1.45 


1.50 


4 


.48 


.52 


.56 


.60 


.64 


.68 


.72 


.76 


.80 


.84 


.88 


.92 


.98 


1.00 


1.04 


1.08 


1.12 


1.16 


1.20 


8 


.36 


.39 


.42 


.45 


.48 


.51 


.54 


.57 


.60 


.63 


.66 


.69 


.72 


.75 


.78 


.81 


.84 


.87 


.90 


2 


.24 


.26 


.28 


.30 


.32 


.34 


.36 


.88 


.40 


.42 


.44 


.46 


.48 


.50 


.52 


.64 


.66 


.68 


.60 


1 


.12 


.13 


.14 


.16 


.16 


.17 


.18 


.19 


.20 


.2: 


.22 


.23 


.24 


.25 


.26 


.27 


.28 


.29 


.30 



18 



272 



Testing Milk and Its Products, 



Table Vin. Pounds of fat in I to (000 lbs. of creiam {continued). 



4-9 


31 


32 


33 


34 


85 


36 


37 


38 


39 


40 


41 


42 


43 


44 


45 


46 


47 


48 


49 


50 


ta 

1000 


810 


820 


380 


340 


350 


860 


870 


880 


390 


400 


410 


420 


430 


440 


450 


460 


470 


480 


490 


600 


900 


279 


288 


297 


306 


315 


324 


333 


842 


851 


860 


309 


378 


387 


896 


405 


414 


423 


432 


441 


450 


800 


248 


256 


264 


272 


280 


288 


296 


304 


312 


320 


328 


836 


844 


352 


3H0 


868 


376 


884 


892 


400 


700 


217 


224 


231 


238 


245 


252 


259 


266 


273 


280 


287 294 


801 


308 


315 


322 


829 


836 


848 


3.50- 


600 


isal 


192 


198 


204 


210 


216 


2:^2 


228 


234 


240 


246 252 


258 


264 


270 


276 


282 


288 


294 


800 


600 


155 


160 


165 


170 


175 


180 


185 


190 


195 


200 


205 211) 


215 


2-20 


225 


230 


235 


240 


245 


250 


401) 


124 


128 


132 


186 


140 


144 


148 


152 


166 


160 


164 


168 


172 


176 


180 


184 


188 


192 


196 


200 


800 


93 


96 


99 


102 


ia5 


108 


111 


114 


117 


120 


123 


126 


129 


132 


135 


188 


141 


144 


147 


150 


200 


62 


64 


66 


68 


70 


72 


74 


76 


78 


80 


82 


84 


86 


88 


90 


92 


94 


96 


98 


100 


100 


81 


82 


8:1 


34 


85 


36 


37 


88 


89 


40 


41 


42 


43 


44 


45 


46 


47 


48 


49 


60 


90 


27.9 


28.8 


29.7 


30.6 


31.5 


32.4 


33.3 


34.2 


35.1 


86.0 


36.9 


37.8 


38.7 


39.6 


40.5 


41.4 


42.3 


48.2 


44.1 


46.0 


80 


24.8 


2i.6 


26.4 


27.2 


28.0 


28.8 


29.6 


30.4 


21.2 


32.0 


82.8 


33.6 


34.4 


35.2 


36.0 86.8 


37.688.4 


30.2 


40.0 


70 


21.7 


22.4 


23.1 


23.8 


2^.6 


25.2 


25.9 


26.6 


27.8 


28.0 


28.7 


29.4 


30.1 


30 8 


31.5:32.2 


32.9 88.6 


34.8 


&5.0 


60 


18.6 


19.2 


19.8 


20.4 


21.0 


21.6 


22.2 


22.8 


28.4 


24.0 


24.6 


25.2 


25.8 


26.4 


27.0 


27.6 


28.2.28.8 


29.4 


80.0 


50 


15.6 


16.0 


16.5 


17.0 


17.5 


18.0 


18.5 


19.0 


19.6 


20.0 


20.5 


21.0 


21.5 


22.0 


22.6 


23.0 


•23.5 24.0 


24.5 


25.0 


40 


12.4 


12.8 


13.2 


13.6 


14.0 


14.4 


14.8 


15.2 


15.6 


16.0 


16.4 


16.8 


17.2 


17.6 


18.0 


18.4 


18.8 19.2 


19.6 


20.0 


80 


9.3 


9.6 


9.9 


10.2 


10.5 


10.8 


11.1 


11.4 


11.7 


12.0 


12.3 


12.6 


12.9 


13.2 


18.5 


18.8 


14.1 


14.4 


14.7 


16.0 


20 


6.2 


6.4 


6.6 


6.8 


7.0 


7.2 


7.4 


7.6 


7.8 


8.0 


8.2 


8.4 


8.6 


8.8 


9.0 


9.2 


9.4 


9.6 


9.8 


10.0 


10 


3.1 


8.2 


3.3 


3.4 


3.5 


3.6 


3.7 


3.8 


8.9 


4.0 


4.1 


4.2 


4.3 


4.4 


4.5 


4.6 


4.7 


4.8 


4.9 


6.0 


9 


2.79 


2.88 


2.97 


3.06 


3.15 


3.24 


8.33 


3.42 


3.51 


3.60 


3.69 


3.78 


3.87 


3.96 


4.95 


4.14 


4.23 


4.82 


4.41 


4.50 


8 


2.48 


2.50 


2.61 


2.72 


2.80 


2.88 


2.9G 


8.04 


3.12 


3.20 


3.28 


3.86 


3.44 


8.52 


3.608.68 


8.76 3.84 


3.924.00 


7 


2.17 


2.24 


2.81 


2.38 


2.45 


2.52 


2.59 


2.66 


2.73 


2.80 


2.87 


2.94 


8.01 


3.08 


3.15 8.22 


3.29 


8.86 


8.433.50 


6 


1.86 


1.92 


1.98 


2.04 


2.10 


2.16 


2.22 


2.28 


2.34 


2.40 


2.46 


2.62 


2.58 


2,64 


2.70 


2.76 


2.82 


2.88 


2.94 


8.00 


6 


1.55 


1.60 


1.65 


1.70 


1.75 


1.80 


1.85 


1.90 


1.95 


2.00 


2.05 


2.10 


2.16 


2.20 


2.26 


2.80 


2.35 


2.40 


2,45 


2.50 


4 


1.24 


1.28 


1.32 


1.86 


1.40 


1.44 


1.48 


1.52 


1.66 


1.60 


1.64 


1.68 


1.72 


1.76 


1.80 


1.84 


1.88 


1.92 


1.06 


2.00 


8 


.93 


.96 


.99 


1.02 


l.Oi 


1.08 


1.11 


1.14 


1.17 


1.20 


1.28 


1.26 


1.29 


1.32 


1.35 


1.88 


1.41 


1.44 


1,47 


1.60 


2 


.62 


.64 


.66 


.68 


.70 


.72 


.74 


.76 


.78 


.80 


.82 


.84 


.86 


.88 


.90 


.92 


.94 


.96 


.98 


1.00 


1 


.81 


.32 


.33 


.34 


.35 


M 


.87 


.38 


.89 


.40 


.41 


.42 


.48 


.44 


.45 


.46 


.47 


.48 


.49 


.60 



Appendix. 



273 



fabte IX. Amount due for butter fat, in dollars and cents, at 
12 to 25 cents per pound. 

(See directions for use, page Uf.) 



I 



Qui 9 
O 
P. 



12 

12i 
12i 

12| 

13 

13J 
13^ 
131 

14 
14i 

14^ 
14| 

15 
15J 

15^ 
151 

16 
161 
16^ 
16J 

17 

171 
17i 
17f 

18 

18i 
18^ 
18| 



Pounds of butter fat. 



1,000 



120.00 
122.50 
125.00 
127.60 

130.00 
132.50 
135.00 
137.50 

140.00 
142.50 
145.00 
147.50 

150.00 
152.50 
155.00 
157.50 

160.00 
162.50 
165.00 
167.50 

170.00 
172.50 
175.00 
177.60 

180.00 
182.50 
185.00 
187.60 



1,000 



900 



800 



108.00 
110.25 
112.50 
114.75 102.00 

117.00104.00 



96.00 

98.00 

100.00 



119.2.5 
121.50 
123.75 

126.00 
128.25 
130.50 
132.75 

135.00 
137.25 
139.50 
141.75 

144.00 
146.25 
148.50 
150.75 

153.00 
155.25 
157.50 
159.75 

162.00 
164.25 
166.50 
168.75 



900 



106.00 



700 



$ 

84.00 
85.75 
87.50 
89.25 

91.00 
92.75 



108.00 94.50 
110.00 96.25 



112.00 
114.00 
116.00 
118.00 

120.00 
122.00 
124.00 
126.00 

128.00 
130.00 
132.00 
134.00 



98.00 

99.75 

101.50 

103.25 

105.00 
106.75 
108.50 
110.25 

112.00 
113.75 
115.50 
117.25 



136.00119.00 



600 



72.00 
73.50 
75.00 
76.50 

78.00 
79.50 
81.00 
82.50 

84.00 
85.50 
87.00 
88.60 

90.00 
91.50 
93.00 
94.60 

96.00 

97.50 

90.00 

100.50 



138.00 
140.00 
142.00 

144.00 
146.00 
148.00 
150.00 



800 



120.75 
122.50 
124.25 

126.00 
127.75 
129.50 
131.25 



700 



102.00 85.00 



500 



60.00 
61.25 
62.50 
63.75 

65.00 
66.25 
67.50 
68.75 

70.00 
71.25 
72.50 
73.76 

7r^oo 

76.25 
77.50 
78.75 

80.00 
81.25 

82.50 
83.75 



103.50 
105.00 
106.50 

108.00 
109.50 
111.00 
112.50 



600 



86. 

87.50 
87.75 

90.00 
91.25 
92.50 
93.76 



500 



400 



48.00 
49.00 
50.00 
51.00 

52.00 
53.00 
54.00 
55.00 

56.00 
57.00 
58.00 
59.00 

60.00 
61.00 
62.00 
63.00 

64.00 
65.00 
66.00 
67.00 

68.00 
69.00 
70.00 
71.00 

72.00 
73.00 
74.00 
75.00 



300 



400 



36.00 
36.75 
37.50 
38.25 

39.00 
39.75 
40.50 
41.25 

42.00 
42.75 
43.50 
44.25 

45.00 
45.75 
46.50 
47.25 

48.00 
48.75 
49.50 
50.25 

51.00 
51.75 
52.50 
53.25 

54.00 
54.75 
55.50 
56v25 



300 



200 



24.00 
24.50 
25.00 
25.50 

26.00 
26.50 
27.00 
27.50 

28.00 
28.50 
29.00 
29.60 

30.00 
30.50 
31.00 
31.60 

32.00 
32.50 
33.00 
33.50 

34.00 
34.50 
35.00 
36.50 

36.00 
36.50 
37.00 
37 60 



200 



100 



12.00 
12.25 
12.50 
12.75 

13.00 
13.25 
13.50 
13.75 

14.00 
14.25 
14.50 
14.75 

15.00 
15.25 
15.50 
15.75 

16.00 
16.25 
16.50 
16.75 

17.00 
17.25 
17.50 
17.75 

18.00 
18.25 
18.60 
18.76 



100 



•g 



274 



Testing Milk and Its Products. 



Table IX. Amount due for butter fat {Continued), 





Pounds of butter fet. 


33. 


■Cfl 
o 


1,000 


900 


800 


700 


600 


500 


400 


300 


200 


100 


00 


19 
19i 

19| 

20 

20^ 
20^ 
20| 

21 
21i 
21^ 
21| 

22 
22i 
22^ 
22f 

23 

23J 

23i 
23| 

24 

24i 
241 
24| 
25 


$ 

190.00 
192.50 
195.00 
197.50 

200.00 
202.50 
205.00 
207.50 

210.00 
212.50 
215.00 
217.50 

220.00 
222.50 
225.00 

227.50 

230.00 
232.50 
235.00 
237.50 

240.00 
242.50 
245.00 
247.50 
250.00 


$ 

171.00 
173.25 
175.50 
177.75 

180.00 
182.25 
184.50 
186.75 

189.00 
191.25 
193.50 
195.75 

198.00 
200.25 
202.50 
204.75 

207.00 
209.25 
211.50 
213.75 

216.00 
218.25 
220.50 
222.75 
225.00 


152.00 
154.00 
156.00 
158.00 

160.00 
162.00 
164.00 
166.00 

168.00 
170.00 
172.00 
174.00 

176.00 
178.00 
180.00 
182.00 

184.00 
186.00 
188.00 
190.00 

192.00 
194.00 
196.00 
198.00 
200.00 


$ 

133.00 
134.75 
130.50 
138.25 

140.00 
141.75 
143.50 
145.25 

147.00 
148.75 
150.50 
152.25 

154.00 
155 . 75 
157.50 
159.25 

161.00 
162.75 
164.50 
166.25 

168.00 
169.75 
171.50 
173.25 
175.00 


114.00 
115.50 
117.00 
118.50 

123.00 
121.50 
123.00 
124.50 

126.00 
127.50 
129.00 
130.50 

132.00 
133.50 
135.00 
136.50 

138.00 
139.. 50 
141.00 
142.50 

144.00 
145.50 
147.00 
148.50 
150.00 


$ 

95.-00 
96.25 
97.50 
98.75 

100.00 
101.25 
102.50 
103.75 

105.00 
106.25 
107.50 
108.75 

110.00 
111.25 
112.50 
113.75 

115.00 
116.25 
117.50 
118.75 

120.00 
121.25 
122.50 
123.75 
125.00 


$ 

76.00 
77.00 
78.00 
79.00 

80.00 
81.00 
82.00 
83.00 

84.00 
85.00 
86.00 
87.00 

88.00 
89.00 
90.00 
91.00 

92.00 
93.00 
94.00 
95.00 

96.00 
07.00 
98.00 
90.00 
100.00 


$ 

57.00 
57.75 
58.50 
59.25 

60.00 
60.75 
61.50 
62.25 

63.00 
03.75 
64.50 
65.25 

66.00 
66.75 
67.50 
68.25 

69.00 
69.75 
70.50 
71.25 

72.00 
72.75 
73.50 
74.25 
75.00 


$ 

38.00 
3S.50 
39.00 
39.50 

40.00 
40.50 
41.00 
41.50 

42.00 
42.50 
43.00 
43.50 

44.00 
44.50 
45.00 
45.50 

46.00 
46.50 
47.00 
47.50 

48.00 
48.50 
49.00 
49.50 
50.00 


$ 

19.00 
19.25 
19.50 
19.75 

20.00 
20.25 
20.50 
20.75 

21.00 
21.25 
21.50 
21.75 

22.00 
22.25 
22.50 
22.75 

23.00 
23.25 
23.50 
23.75 

24.00 
24.25 
24.50 
24.75 

25.00 


19 
19J 
19. 
19! 

20 

20i 
20J 
201 

21 
21\ 
21 J 
21i 

22 

221 

22i 
221 

23 
23i 
23^ 
231 

24 

214 

21^ 

211 
25 




1,000 


900 


800 


700 


600 


500 


400 


300 


200 


100 





Appendix. 



275 



Table X. Relative-value tables. 

(See directions for use, par. 238.) 



i 




Price of 


milk per 100 pounds, in dollars and cents. 




3.0 


.30 


.31 


.33 


.34 


.36 


.37 


.89 


.40 


.42 


.43 


.45 


3.1 


.31 


.33 


.34 


.36 


.37 


.39 


.40 


.42 


.43 


.45 


.46 


3.2 


.32 


.34 


.35 


.37 


.88 


.40 


.42 


.43 


.45 


.46 


.4ft 


3.3 


.33 


.35 


.36 


.38 


.4.J 


.41 


.^3 


.45 


.46 


.48 


.49 


3.4 


.34 


.36 


.37 


.39 


.41 


.42 


.44 


.46 


.48 


.49 


.61 


3.6 


.35 


.37 


.38 


.40 


.42 


.44 


.45 


.47 


.49 


.51 


.5£ 


3.6 


.36 


.38 


.40 


.41 


.43 


.45 


.47 


.49 


.50 


.62 


.64 


3.7 


.37 


.39 


.41 


.43 


.44 


.46 


.48 


.50 


.52 


.54 


.65 


3.8 


.38 


.40 


.42 


.44 


.46 


.47 


.49 


.51 


.53 


.55 


.67 


3.9 


.39 


.41 


.43 


.45 


.47 


.49 


.51 


.53 


.55 


.67 


.58 


4.0 


.40 


.42 


.44 


.46 


.48 


.50 


.52 


.54 


.56 


.58 


.6C 


4.1 


.41 


.43 


.45 


.47 


.^0 


.51 


.58 


.55 


.57 


.59 


.61 


4.2 


.42 


.44 


.46 


.48 


.50 


.52 


.55 


.57 


.59 


.61 


M 


4.3 


.43 


.45 


.47 


.49 


.52 


.54 


.56 


.58 


.60 


.62 


.64 


4.4 


.44 


.46 


.48 


.61 


.53 


.55 


.57 


.59 


.62 


.64 


.6e 


4.5 


.45 


.47 


.49 


.52 


.54 


.56 


.58 


.61 


.63 


.65 


.67 


4.6 


.46 


.48 


.51 


.53 


.55 


.57 


.60 


.62 


.64 


.67 


.6f 


4.7 


.47 


.49 


.52 


.54 


.50 


.59 


.61 


.63 


.66 


.68 


.7C 


4.8 


.48 


.50 


.53 


.55 


58 


.60 


.62 


.65 


.67 


.70 


.72 


4.9 


.49 


.51 


.54 


.56 


.59 


.61 


.64 


.66 


.69 


.71 


.78 


5.0 


.50 


.52 


.55 


.57 


.60 


.62 


.65 


.67 


.70 


.72 


.75 


5.1 


.51 


.54 


.56 


.59 


.61 


.64 


.66 


.69 


.71 


.74 


.76 


5.2 


.52 


.55 


.57 


.60 


.62 


.65 


.68 


.70 


.78 


.75 


.78 


5.3 


.53 


.56 


.58 


.61 


.64 


.66 


.69 


.72 


.74 


.77 


.7£ 


5.4 


.54 


.57 


.59 


.62 


.65 


.67 


.70 


.73 


.76 


.78 


.81 


5.5 


.55 


.58 


.60 


.63 


.66 


.69 


.71 


.74 


.77 


.80 


.8^ 


5.6 


.56 


.59 


.62 


.64 


.67 


.70 


.73 


.76 


.78 


.81 


.84 


5.7 


.57 


.60 


.63 


.66 


.68 


.71 


.74 


.77 


.80 


.88 


.85 


5.8 


.58 


.61 


.64 


.67 


.70 


.72 


.75 


.78 


.81 


.84 


.87 


5.9 


.59 


.62 


.65 


.68 


.71 


.74 


.77 


.80 


.83 


.86 


.88 


6.0 


.60 


.63 


.66 


.09 


.72 


.75 


.78 


.81 


.84 


.hT 


.90 



276 



Testing Milk and Its Products. 



Table X. Relative-value tables ( Continued), 



P 


Price of milk per 100 pounds, in dollars and cents. 


3.0 


.46 


.48 


.49 


.51 


.52 


.54 


.55 


.57 


.58 


.60 


8.1 


.48 


.50 


.51 


.53 


.54 


.56 


.57 


.59 


.60 


.62 


3.2 


.50 


.51 


.53 


.54 


.56 


.58 


.59 


.61 


.62 


.64 


3.3 


.51 


.53 


.54 


.56 


.58 


.59 


.61 


.63 


.64 


.66 


3.4 


.53 


.54 


.56 


.58 


.59 


.61 


.63 


.65 


.66 


.68 


8.5 


.54 


.66 


.68 


.69 


.61 


.63 


.65 


.66 


.68 


.70 


8.6 


.66 


.68 


.69 


M 


.68 


.66 


.67 


.68 


.70 


.72 


8.7 


.&7 


.69 


.61 


.68 


.65 


.67 


.68 


.70 


.72 


.74 


3.8 


.69 


.61 


.63 


.65 


.66 


.68 


.70 


.72 


.74 


.76 


8.9 


.60 


.62 


.64 


.66 


.68 


.70 


.72 


.74 


.76 


.78 


4.0 


.62 


.64 


.66 


.68 


.70 


.72 


.74 


.76 


.78 


.80 


4.1 


.64 


.66 


.68 


.70 


.72 


.74 


.76 


.78 


.80 


.82 


4.2 


.65 


.67 


.69 


.71 


.73 


.76 


.78 


.80 


.82 


.84 


4.3 


.67 


.69 


.71 


.73 


.75 


.77 


.80 


.82 


.84 


.86 


4.4 


.68 


.70 


.73 


.75 


.77 


.79 


.81 


.84 


.86 


.88 


4.5 


.70 


.72 


.74 


.76 


.79 


.81 


.83 


.85 


.88 


.90 


4.6 


.71 


.74 


.76 


.78 


.80 


.83 


.85 


.87 


.90 


.92 


4.7 


.73 


.75 


.78 


.80 


.82 


.85 


.87 


.89 


.92 


.94 


4.8 


.74 


.77 


.79 


.82 


.84 


.86 


.89 


.91 


.94 


.96 


4.9 


.76 


.78 


.81 


.83 


.86 


.88 


.91 


.93 


.96 


.98 


6.0 


.77 


.80 


.82 


.85 


.87 


.90 


.92 


.95 


.97 


1.00 


5.1 


.79 


.82 


.84 


.87 


.89 


.92 


.94 


.97 


.99 


1.02 


6.2 


.81 


.83 


.86 


.88 


.91 


.94 


.96 


.99 


1.03 


1.04 


5.3 


.83 


.85 


.87 


.90 


.93 


.95 


.98 


1.01 


1.03 


1.06 


6.4 


.84 


.86 


.89 


.92 


.94 


.97 


1.00 


1.03 


1.05 


1.08 


5.5 


.85 


.88 


.91 


.93 


.96 


.99 


1.02 


1.04 


1.07 


1.10 


5.6 


.87 


.90 


.92 


.95 


.98 


1.01 


1.04 


1.06 


1.09 


1.12 


5.7 


.88 


.91 


.94 


.97 


1.00 


1.03 


1.05 


1.08 


1.11 


1.14 


5.8 


.90 


.93 


.96 


.99 


1.01 


1.04 


1.07 


1.10 


1.13 


1.16 


5.9 


.91 


.94 


.97 


1.00 


1.03 


1.06 


1.09 


1.12 


1.15 


1.18 


6.0 


.93 


.96 


.99 


1.02 


1.05 


1.08 


1.11 


1.14 


1.17 


1.20 



Appendix. 



277 



Table X. Relative-value tables {Continued). 



a 

H 


Price of milk per 100 pounds, la dollars and cents. 


3.0 


.61 


.63 


.64 


.66 


.67 


.69 


.70 


.72 


.73 


.76 


3.1 


.64 


.65 


.67 


.68 


.70 


.71 


.78 


.74 


.76 


.78 


3.2 


.66 


.67 


.69 


.70. 


.72 


.74 


.75 


.77 


.78 


.80 


8.3 


.68 


.69 


.71 


.73 


.74 


.76 


.78 


.79 


.81 


.83 


3.4 


.70 


.71 


.73 


.75 


.76 


.78 


.80 


.82 


.83 


.85 


3.5 


.72 


.73 


.75 


.77 


.79 


.80 


.82 


.84 


.86 


.88 


3.6 


.74 


.76 


.77 


.79 


.81 


.83 


.85 


.86 


.88 


.90 


3.7 


.76 


.78 


.80 


.81 


.83 


.85 


.87 


.89 


.91 


.93 


3.8 


.78 


.80 


.82 


.84 


.85 


.87 


.89 


.91 


.93 


.95 


3.9 


.80 


.82 


.84 


.86 


.88 


.90 


.92 


.94 


.90 


.98 


4.0 


.82 


.84 


.86 


.88 


.90 


.92 


.94 


.96 


.98 


1.00 


4.1 


.84 


.86 


.88 


.90 


.92 


.94 


.96 


.98 


1.00 


1.03 


4.2 


.86 


.88 


.90 


.92 


.94 


.97 


.99 


1.01 


1.03 


1.05 


4.3 


.88 


.90 


.92 


.95 


.97 


.99 


1.01 


1.03 


1.05 


1.08 


4.4 


.90 


.92 


.95 


.97 


.99 


1.01 


1.03 


1.06 


1.08 


1.10 


4.5 


.92 


.94 


.97 


.99 


1.01 


1.03 


1.06 


1.08 


1.10 


1.13 


4.6 


.94 


.97 


.99 


1.01 


1.03 


1.06 


1.08 


1.10 


1.13 


1.15 


4.7 


.96 


.99 


1.01 


1.03 


1.06 


1.08 


1.10 


1.13 


1.15 


1.18 


4.8 


.98 


1.01 


1.03 


1.06 


1.08 


1.10 


1.18 


1.15 


1.18 


1.20 


4.9 


1.00 


1.03 


1.05 


1.08 


1.10 


1.13 


1.15 


1.18 


1.20 


1.23 


6.0 


1.02 


1.05 


1.07 


1.10 


1.12 


1.15 


1.18 


1.20 


1.23 


1.25 


5.1 


1.05 


1.07 


1.10 


1.12 


1.15 


1.17 


1.20 


1.22 


1.25 


1.27 


5.2 


1.07 


1.09 


1.12 


1.14 


1.17 


1.20 


1.22 


1.25 


1.27 


1.30 


5.3 


1.09 


1.11 


1.14 


1.17 


1.19 


1.22 


1.25 


1.27 


1.30 


1.32 


5.4 


1.11 


1.13 


1.16 


1.19 


1.21 


1.24 


1.27 


1.30 


1.32 


1.3o 


5.5 


1.13 


1.15 


1.18 


1.21 


1.24 


1.26 


1.29 


1.32 


1.35 


1.88 


5.6 


1.15 


1.18 


1.20 


1.2;} 


1.20 


1.29 


1.32 


1.34 


1.37 


1.40 


5.7 


1.17 


1.20 


1.23 


1.2-5 


1.28 


1.31 


1.34 


1.37 


1.39 


1.43 


5.8 


1.19 


1.22 


1.25 


1.28 


1.30 


1.33 


1.30 


1.39 


1.42 


1.45 


5.9 


1.21 


1.24 


1.27 


1.30 


1.33 


1.36 


1.39 


1.42 


1.45 


1.48 


6.0 


1.23 


1.26 


1.29 


1.32 


1.35 


1.38 


1.41 


1.44 


1.47 


1.50 



278 



Testing Milk and Its Products. 



Table X. Relative-value tables {Continued). 



4-> 

CI 

^ -J 


— «, ___ 

Price of milk por 100 pounds, In dollars and cents. 


3.0 


.76 


.78 


.79 


.81 


.82 


.84 


.85 


.87 


.88 


.90 


3.1 


.79 


.81 


.82 


.84 


.85 


.87 


.88 


.90 


.91 


.93 


3.2 


.82 


.8H 


.85 


.86 


.88 


.90 


.91 


.93 


.94 


.96 


3.3 


.84 


.86 


.87 


.89 


.91 


.92 


.94 


.96 


.97 


.99 


3.4 


.87 


.88 


.90 


.92 


.93 


.95 


.97 


.99 


1.00 


1.02 


3.5 


.89 


.91 


.93 


.94 


.96 


.98 


1.00 


1.01 


1.03 


1.05 


3.6 


.92 


.94 


.95 


.97 


.99 


1.00 


1.03 


1.04 


1.06 


1.08 


3.7 


.94 


.96 


.98 


1.00 


1.02 


1.03 


1.05 


1.07 


1.09 


1.11 


8.8 


.07 


.99 


1.01 


1.03 


1.04 


1.06 


1.08 


1.10 


1.12 


1.14 


3.9 


.99 


1.01 


1.03 


1.05 


1.07 


1.09 


1.11 


1.13 


1.15 


1.17 


4.0 


1.02 


1.04 


1.06 


1.08 


1.10 


1.12 


1.14 


1.16 


1.18 


1.20 


4.1 


1.05 


1.07 


1.09 


1.11 


1.13 


1.15 


1.17 


1.19 


1.21 


1.23 


4.2 


1.07 


1.09 


1.11 


1.13 


1.15 


1.18 


1.20 


1.22 


1.24 


1.26 


4.3 


1.10 


1.12 


1.14 


1.16 


1.18 


1.20 


1.23 


1.25 


1.27 


1.29 


4.4 


1.12 


1.14 


1.17 


1.19 


1.21 


1.23 


1.25 


1.28 


1.30 


1.32 


4.5 


1.15 


1.17 


1.19 


1.21 


1.24 


1.26 


1.28 


1.30 


1.33 


1.35 


4.6 


1.17 


1.20 


1.22 


1.24 


1.26 


1.29 


1.31 


1.33 


1.36 


1.38 


4.7 


1.20 


1.22 


1.25 


1.27 


1.29 


1.32 


1.34 


1.36 


1.39 


1.41 


4.8 


1.22 


1.25 


1.27 


1.30 


1.32 


1.34 


1.37 


1.39 


1.42 


1.44 


4.9 


1.25 


1.27 


1.30 


1.32 


1.35 


1.37 


1.40 


1.42 


1.45 


1.47 


5.0 


1.27 


1.30 


1.32 


1.35 


1.37 


1.40 


1.42 


1.45 


1.47 


1.50 


5.1 


1.30 


1.33 


1.35 


1.38 


1.40 


1.43 


1.45 


1.48 


1.50 


1.53 


5.2 


1.33 


1.35 


1.37 


1.40 


1.43 


1.46 


1.48 


1.51 


1.53 


1.66 


6.3 


1.35 


1.38 


1.40 


1.43 


1.46 


1.48 


1.51 


1.54 


1.56 


1.59 


5.4 


1.38 


1.40 


1.43 


1.46 


1.48 


1.51 


1.54 


1.57 


1.59 


1.62 


5.5 


1.40 


1.43 


1.46 


1.48 


1.51 


1.54 


1.57 


1.60 


1.62 


1.65 


5.6 


1.43 


1.46 


1.48 


1.51 


1.54 


1.57 


1.60 


1.62 


1.65 


1.68 


5.7 


1.45 


1.48 


1.51 


1.54 


1.57 


1.60 


i.62 


1.65 


1.68 


1.71 


5.8 


1.48 


1.51 


1.54 


1.57 


1.59 


1.62 


1.65 


1.68 


1.71 


1.74 


5.9 


1.50 


1.53 


1.56 


1.59 


1.62 


1.65 


1.68 


1.71 


1.74 


1.77 


6.0 


1.53 


1.56 


1.59 


1.62 


1.65 


1.68 


1.71 


1.74 


1.77 


1.80 



Appe7idix. 



279 



fable XI. Butter chart, showiny calculated yield of butter (in 
^^bs.) from I to 10,000 lbs. of milk, testing 3.0 to 5.3 per 
cent. (See directions for use, p. 266.) 



«3 

1 


3.00 


3.10 


3.20 


3.80 


3.40 


3.50 


3.60 


3.70 


3.80 


3.90 


4.00 


4.10 


t 


Milk, 


























Milk, 


lbs. 


























lbs. 


10,000 


325 


336 


348 


360 


371 


383 


394 


406 


418 


429 


441 


452 


10,000 


9,000 


293 


302 


313 


324 


334 


345 


355 


365 


376 


386 


397 


407 


9,000 


8,000 


260 


269 


278 


288 


297 


306 


315 


325 


334 


343 


353 


362 


8,000 


7,000 


228 


235 


244 


252 


260 


268 


276 


284 


293 


300 


309 


316 


7,000 


6,000 


195 


202 


209 


216 


223 


230 


236 


244 


251 


257 


265 


271 


6,000 


5,000 


163 


168 


174 


180 


186 


192 


197 


203 


209 


215 


221 


226 


5,000 


4,000 


130 


134 


139 


144 


148 


153 


158 


162 


167 


172 


176 


181 


4,000 


3,000 


97.5 


101 


104 


108 


111 


115 


118 


122 


125 


129 


132 


136 


3,000 


2,000 


65.0 


67.2 


69.6 


72.0 


74.2 


76.6 


78.8 


81.2 


83.6 


85.8 


88.2 


90.4 


2,000 


1,000 


32.5 


33.6 


34.8 


36.0 


37.1 


38.3 


39.4 


40.6 


41.8 


43.9 


44.1 


45.2 


1,000 


900 


29.3 


30.2 


31.3 


32.4 


33.4 


34.5 


35.5 


36.5 


37.6 


38.6 


39.7 


40.7 


900 


800 


26.0 


26.9 


27.8 


28.8 


29.7 


30.6 


31.5 


32.5 


33.4 


34.3 


35.3 


36.2 


800 


700 


22.8 


23.5 


24.4 


25.2 


26.0 


26.8 


27.6 


28.4 


29.3 


30.0 


30.9 


31.6 


700 


600 


19.5 


20.2 


20.9 


21.6 


22.3 


23.0 


23.6 


24.4 


25.1 


25.7 


26.5 


27.1 


600 


500 


16.3 


16.8 


17.4 


18.0 


18.6 


19.2 


19.7 


20.3 


20.9 


21.5 


22.1 


22.6 


600 


400 


13.0 


13.4 


13.9 


14.4 


14.8 


15.3 


15.8 


16.2 


16.7 


17.2 


17.6 


18.1 


400 


300 


9.7 


10.1 


10.4 


10.8 


11.1 


11.5 


11.8 


12.2 


12.5 


12.9 


13.2 


13.6 


300 


200 


6.5 


6.7 


6.9 


7.2 


7.4 


7.0 


7.9 


8.1 


8.3 


8.6 


8.8 


9.0 


200 


100 


3.2 


3.4 


3.6 


3.6 


3.7 


3.8 


3.9 


4.1 


4.2 


4.3 


4.4 


4.5 


100 


90 


2.9 


3.0 


3.1 


3.2 


3.3 


3.4 


3.6 


3.6 


3.7 


3.8 


3.9 


4.1 


90 


80 


2.6 


2.7 


2.8 


2.9 


3.0 


3.1 


3.2 


3.3 


3.4 


3.4 


3.5 


3.6 


80 


70 


2.3 


2.3 


2.4 


2.5 


2.6 


2.7 


2.8 


2.8 


2.9 


3.0 


3.1 


3.2 


70 


60 


1.9 


2.0 


2.1 


2.2 


2.2 


2.3 


2.4 


2.4 


2.6 


2.6 


2.7 


2.7 


60 


50 


1.6 


1.7 


1.7 


1.8 


1.9 


1.9 


2.0 


2.0 


2.1 


2.2 


2.2 


2.3 


60 


40 


1.3 


1.3 


1.4 


1.4 


1.5 


1.5 


1.6 


1.6 


1.7 


1.7 


1.8 


1.8 


40 


30 


1.0 


1.0 


1.0 


1.1 


1.1 


1.2 


1.2 


1.2 


1.8 


1.3 


1.3 


1.4 


80 


20 


.6 


.7 


.7 


.7 


.7 


.8 


.8 


.8 


.8 


.9 


.9 


.9 


20 


10 


.8 


.8 


.4 


.4 


.4 


.4 


.4 


.4 


.4 


.4 


.4 


.6 


10 





.8 


.3 


.3 


.3 


.3 


.3 


.4 


.4 


.4 


A 


.4 


.4 


9 


8 


.8 


.3 


.8 


.8 


.8 


.3 


.3 


.3 


.3 


.8 


.4 


.4 


8 


7 


.2 


.2 


.2 


.8 


.8 


.3 


.3 


.8 


.3 


.3 


.3 


.3 


7 


6 


.2 


.2 


.2 


.2 


.2 


.2 


.2 


.2 


.3 


.3 


.3 


.3 


6 


5 


.2 


.2 


.2 


.2 


.2 


.2 


.2 


.2 


.2 


.2 


.2 


.2 


5 


4 


.1 


.1 


.1 


.2 


.2 


.2 


.2 


.2 


.2 


.2 


.2 


.2 


4 


8 


.1 


.1 


.1 


.1 


.1 


.1 


.1 


.1 


.1 


.1 


.1 


.1 


3 


2 


.1 


.1 


.1 


.1 


.1 


.1 


.1 


.1 


.1 


.1 


.1 


.1 


2 


1 


••••cc* 
























1 


























1 


3.00 


3.10 


3.20 


3.30 


3.40 


3.50 


3.60 


3.70 


3.80 


3.90 


4.00 


4.10 





280 Testing Milk and Its Products. 

Table \l. Butter chart ( Continued)* 



CO 


4.20 


4.30 


4.40 


4.50 


4.60 


4.70 


4.80 


4.90 


5.00 


5.10 


5.20 


1 
5.30 




Milk 
























Milk 


lbs. 


























lbs. 


10,000 


464 


476 


487 


499 


510 


522 


534 


545 


557 


568 


580 


592 


10,000 


9,000 


418 


428 


438 


449 


459 


470 


481 


491 


501 


511 


522 


533 


9,000 


8,000 


371 


381 


390 


399 


408 


418 


427 


436 


446 


454 


464 


474 


8,000 


7,000 


325 


333 


341 


349 


357 


365 


374 


382 


390 


.398 


406 


414 


7,000 


6,000 


278 


286 


292 


299 


306 


313 


320 


327 


334 


341 


348 


355 


6,000 


5,000 


232 


238 


244 


250 


255 


261 


267 


273 


279 


284 


290 


296 


5,000 


4,000 


186 


190 


195 


200 


204 


209 


214 


218 


223 


227 


232 


237 


4,000 


3,000 


139 


143 


146 


150 


153 


157 


160 


164 


167 


170 


174 


17S 


3,000 


2,000 


92.8 


95.2 


97.4 


99.8 


102 


104 


107 


109 


111 


114 


116 


lis 


2,000 


1,000 


46.4 


47.6 


48.7 


49.9 


51.0 


52.2 


53.4 


54.5 


55.7 


56.8 


58.0 


59.2 


1,000 


900 


41.8 


42.8 


43.8 


44.9 


45.9 


47.0 


48.1 


49.1 


50.1 


51.1 


52.2 


53.3 


900 


800 


37.1 


38.1 


39.0 


39.9 


40.8 


41.8 


42.7 


43.6 


44.6 


45.4 


46.4 


47.4 


800 


700 


32.5 


33.3 


34.1 


34.9 


35.7 


36.5 


37.4 


38.2 


39.0 


39.8 


40.6 


41.4 


700 


600 


27.8 


28.6 


29.2 


29.9 


30.6 


31.3 


32.0 


32.7 


33.4 


34.1 


34.8 


35.5 


600 


500 


23.2 


23.8 


24.4 


25.0 


25.5 


26.1 


26.7 


27.3 


27.9 


28.4 


29.0 


29.6 


500 


400 


18.6 


19.0 


19.5 


20.0 


20.4 


20.9 


21.4 


21.8 


22.3 


22.7 


23.2 


23.7 


400 


300 


13.9 


14.3 


14.6 


15.0 


15.3 


15.7 


16.0 


16.4 


16.7 


17.0 


17.4 


17.8 


300 


200 


9.3 


9.5 


9.7 


10.0 


10.2 


10.4 


10.7 


10.9 


11.1 


11.4 


11.6 


11.8 


200 


100 


4.6 


4.8 


4.9 


5.0 


5.1 


5.2 


5.3 


5.5 


5.6 


5.7 


5.8 


5.9 


100 


90 


4.2 


4.3 


4.4 


4.5 


4.6 


4.7 


4.8 


4.9 


5.0 


5.1 


5.2 


5.3 


90 


80 


3.7 


3.8 


3.9 


4.0 


4.1 


4.2 


4.3 


4.4 


4.5 


4.5 


4.6 


4.7 


80 


70 


3.3 


3.3 


3.4 


3.5 


3.6 


3.7 


3.7 


3.8 


3.9 


4.0 


4.1 


4.1 


70 


60 


2.8 


2.9 


2.9 


3.0 


3.1 


3.1 


3.2 


3.3 


3.3 


3.4 


3.5 


3.6 


60 


50 


2.3 


2.4 


2.4 


2.5 


2.6 


2.6 


2.7 


2.7 


2.8 


2.8 


2.9 


3.0 


50 


40 


1.9 


1.9 


2.0 


2.0 


2.0 


2.1 


2.1 


2.2 


2.2 


2.3 


2.3 


2.4 


40 


30 


1.4 


1.4 


1.5 


1.5 


1.5 


1.6 


1.6 


1.6 


1.7 


1.7 


1.7 


1.8 


30 


20 


.9 


1.0 


1.0 


1.0 


1.0 


1.0 


1.1 


1.1 


1 1 


1.1 


1.2 


1.2 


20 


10 


.5 


.5 


.5 


.5 


.5 


.5 


.5 


.6 


.6 


.6 


.6 


.6 


10 


9 


.4 


.4 


.4 


.5 


.5 


.5 


.5 


.5 


.5 


.5 


.5 


.5 


9 


8 


.4 


.4 


.4 


.4 


.4 


.4 


.4 


.4 


.5 


.5 


.5 


.5 


8 


7 


.3 


.3 


.3 


.4 


.4 


.4 


.4 


.4 


.4 


.4 


.4 


.4 


7 


6 


.3 


.3 


.3 


.3 


.3 


.3 


.3 


.3 


.3 


.3 


.4 


.4 


6 


5 


.2 


.2 


.2 


.3 


.3 


.3 


.3 


.3 


.3 


.3 


.3 


.3 


5 


4 


.2 


.2 


.2 


.2 


.2 


.2 


.2 


.2 


.2 


2 


.2 


.2 


4 


3 


.1 


.1 


.2 


.2 


.2 


.2 


.2 


.2 


.2 


'2 


.2 


.2 


3 


2 


.1 


.1 


.1 


.1 


.1 


.1 


.1 


.1 


.1 


[l 


.1 


.1 


2 


1 


.1 


.1 


.1 


.1 


.1 


.1 

4.70 


.1 


.1 


.1 


.1 


.1 


.1 


1 




4.20 


4.30 


4.40 


4.50 


4.60 


4.80 


4.90 


5. CO 


5.10 


5.20 


5.30 





Appendix. 



281 



Table XII. Overrun table, showing pounds of butter from 
one hundred lbs. of milk. (See directions for use, 
pnr. 222.) 



Per 
























Per 


cent. 


1.10 


1.11 


1.12 


1.13 


1.14 


1.15 


1.16 


1.17 


1.18 


1.19 


1.20 


cent. 


fat. 
























fat. 


3.0 


3.30 


3.33 


3.36 


3.39 


3.42 


3.45 


3.48 


3.51 


3.54 


3.57 


3.60 


3.0 


3.1 


3.41 


3.44 


3.47 


3.50 


3.53 


3.57 


3.60 


3.63 


3.6() 


3.68 


3.72 


3.1 


3.2 


3.52 


3.55 


3.58 


3.62 


3.65 


3.68 


3.71 


3.74 


3.7S 


3.81 


3.84 


3.2 


3.3 


3.63 


3. 66 


3.70 


3.73 


3.76 


3.80 


3.83 


3.86 


3.81) 


> 0* 


3.96 


3.3 


3.4 


3.74 


3.77 


3.81 


3.84 


3.88 


3.91 


3.94 


3.98 


4.01 


4.05 


4.08 


3.4 


3.5 


3.85 


3.89 


3.92 


3.90 


3.99 


4.03 


4.00 


4.10 


4.13 


4.17 


4.20 


3.5 


3.6 


3.96 


4.00 


4.03 


4.07 


4.10 


4.14 


4.18 


4.21 


4.25 


4.2S 


4.32 


3.6 


3.7 


4.07 


4.11 


4.14 


4.18 


4.22 


4.26 


4.29 


4.33 


4.37 


4.40 


4.44 


3.7 


3.8 


4.18 


4.22 


4.26 


4.29 


4.33 


4.C7 


'1.41 


4.45 


4. 48 


4.5-J 


4.56 


3.8 


3.9 


4.29 


4^33 


4.37 


4.41 


4.45 


4.49 


4.52 


4.56 


4.60 


4 (54 


4.68 


3.9 


4.0 


4.40 


4.44 


4.48 


4.52 


4.56 


4.60 


4.64 


4.68 


4.72 


4.76 


4.80 


4.0 


4.1 


4.51 


4.55 


4.59 


4.63 


4.67 


4.72 


4.76 


4.80 


4.84 


4.88 


4.92 


4.1 


4.2 


4.62 


4.66 


4.70 


4.75 


4.79 


4.83 


4.87 


4.91 


4.96 


■..00 


5.04 


4.2 


4.3 


4.73 


4.77 


4.82 


4.86 


4.90 


4.95 


4.99 


5.03 


5.07 


5 . 12 


5.16 


4.3 


4.4 


4.84 


4.88 


4.93 


4.97 


5.02 


5.06 


5.10 


5.15 


5.19 


5.24 


5.28 


4.4 


4.5 


4.95 


5.00 


5.04 


5.09 


5.13 


5.18 


5.22 


5.27 


5.31 


5.36 


5.40 


4.5 


4.0 


5.06 


5.11 


5.15 


5.20 


5.24 


5.29 


5.34 


5.38 


5.43 


5.47 


5.52 


4.6 


4.7 


5.17 


5.22 


5.26 


5.31 


5.36 


5.41 


5.45 


5.49 


5.55 


5.59 


5.64 


4.7 


4.8 


5.28 


5.33 


5.38 


5.42 


5.47 


5.52 


5.57 


5.62 


5.66 


5.71 


5.7(i 


4.8 


4.9 


5.39 


5.44 


5.49 


5.54 


5.59 


5.64 


5.68 


5.73 


5.78 


5.83 


5.88 


4.9 


5.0 


5.50 


5 55 


5.60 


5.65 


5.70 


5.75 


5.80 


5.85 


5.90 


5.95 


6.00 


5.0 


5.1 


5.61 


5.66 


5.71 


5.76 


5.81 


5.87 


5.92 


5.97 


6.02 


6.07 


6.12 


5.1 


5.2 


5.72 


5.77 


5.82 


5.88 


5.93 


5.98 


6.03 


6.08 


6.14 


6.19 


6.24 


5.i 


5.3 


5.83 


5.88 


5.94 


5.99 


6.04 


6.10 


6.15 


6.20 


6 . 25 


6.31 


6.36 


5.3 


5.4 


5.94 


5.99 


6.05 


6.10 


6.16 


6.21 


6.26 


6.32 


0.37 


6.43 


6.48 


5.4 


5.5 


6.05 


6.11 


6.16 


6.22 


6.27 


6.33 


6.38 


6.44 


6.49 


6.55 


6.eo 


5.5 


5.6 


6.16 


6.22 


6.27 


6.33 


6.38 


6.44 


6.50 


6.55 


6.61 


6.66 


6.72 


5.6 


5.7 


6.27 


6.33 


6.38 


6.44 


6.50 


6.56 


6.61 


6.67 


6.73 


6.78 


6.84 


5.7 


5.8 


6.38 


(3.44 


6.50 


6.55 


6.61 


6.67 


6.73 


6.79 


6.84 


6.90 


6.96 


5.8 


5.9 


6.49 


6.55 


6.61 


6.67 


6.73 


6.79 


6.84 


6.90 


6.96 


7.02 


7.08 


5.9 


6.0 


6.6C 


6.66 


6.72 


6.78 


/3.84 


6.90 


6.96 


7.02 


7.08 


7.14 


7.20 


6.0 



282 



Testing Milk and Its Products. 



Table XIII. Yield of Cheese from 100 lbs. milk with 2.5 to 
6 per cent, or lat, and lactometer readings from 26 to 30. 

(See par. 224) 



«i 


Lactometer degrees. 


i^ 


(Li 


26 


27 


28 


29 


30 


31 


32 


33 


34 


35 


36 


8^ 

<x> o 

Oh 


2.5 


7.2S 


7.41 


7.54 


7.67 


7.81 


7.94 


8.07 


8.20 


8.33 


8.47 


8.60 


2.5 


2.6 


7.44 


7.57 


7.70 


7.83 


7.96 


8.09 


8.22 


8.35 


8.49 


8.62 


8.76 


2.6 


2.7 


7.59 


7.72 


7.85 


7.99 


8.12 


8.25 


8.38 


8.51 


8.64 


8.77 


8.91 


2.7 


2.8 


7.74 


7.87 


8.00 


8.14 


8.27 


8.40 


8.63 


8.67 


8.80 


8.91 


9.07 


2.8 


2.9 


7.90 


8.03 


8.16 


8.30 


8.44 


8.56 


8.69 


8.82 


8.95 


9.09 


9.22 


2.9 


3.0 


8.05 


8.18 


8.31 


8.45 


8.58 


8.71 


8.84 


8.97 


9.11 


9.24 


9.37 


3.0 


3.1 


8.21 


8.34 


8.47 


8.60 


8.74 


8.87 


9.00 


9.13 


9.26 


9.39 


9.53 


3.1 


3.2 


8.36 


8.49 


8.62 


8.75 


8.89 


9.02 


9.15 


9.28 


9.42 


9.55 


9.68 


3.2 


3.3 


8.52 


8.65 


8.78 


8.91 


9.05 


9.18 


9.31 


9.44 


9.57 


9.70 


9.84 


3.3 


3.4 


8.67 


8.80 


8.93 


9.06 


9.20 


9.33 


9.46 


9.69 


9.73 


9.86 


9.99 


3.4 


3. ft 


8.82 


8.96 


9.09 


9.22 


9.35 


9.48 


9.62 


9.75 


9.88 


10.01 


10.15 


3.5 


3.6 


8.98 


9.11 


9.24 


9.37 


9.50 


9.63 


9.77 


9.90 


10.03 


10.17 


10.30 


3.6 


3.7 


9.13 


9.26 


9.39 


9.52 


9.65 


9.78 


9.92 


10.05 


10.19 


10.32 


10.46 


3.7 


3.h 


9.29 


9.42 


9.55 


9.68 


9.81 


9.94 


lo.O^ 


10.21 


10.34 


10.48 


10.61 


3.8 


3.9 


9.44 


9.57 


9.70 


9.84 


9.97 


10.10 


10.23 


10.36 


10.50 


10.64 


10.77 


3.9 


4.0 


9.60 


9.73 


9.86 


10.00 


10.13 


10.26 


10.39 


10.63 


10.66 


10.79 


10.93 


4.0 


4.1 


9.76 


9.88 


10.02 


.0.15 


10.28 


10.39 


10.54 


10.68 


10.81 


10.94 


11.08 


4.1 


4.2 


9.90 


10.03 


10.17 


10.30 


10.43 


10.57 


10.70 


10.84 


10.97 


11.10 


11.24 


4.2 


4.3 


10.06 


10.19 


10.32 


10.45 


lu.58 


10.72 


10.85 


10.99 


11.12 


11.25 


11.39 


4.3 


4.4 


10.21 


10.34 


10.48 


10.61 


10.74 


10.87 


11.00 


11.14 


11.27 


11.41 


11.65 


4.4 


4.5 


10.36 


10.49 10.63 


10.76 


10.89 


11.03 


11.16 


11.29 


11.42 


11.56 


11.70 


4.5 


4.6 


10.52 


10.65 


10. 7» 


10.92 


11.05 


11.18 


11.31 


11.45 


11.58 


11.71 


11.85 


4.6 


4.7 


10.67 


10.81 


10.94 


11.07 


11.20 


11.34 


11.47 


11.60 


11.73 


11.87 


12.01 


4.7 


4.8 


10.83 


10.96 


11.09 


11.22 


11.36 


11.49 


11.62 


11.76 


11.89 


12.02 


12.16 


4.8 


4.9 


10.98 


11.11 


11.25 


11.3.S 


11.51 


11.65 


11.78 


11.91 


12.04 


12.18 


12.32 


4.9 


5.(1 


11.14 


11.27 


11.40 


11.54 


11.67 


11.80 


11.93 


12.07 


12.20 


12.34 


12.48 


5.0 


5.1 


11.29 


11.42 


11.55 


11.69 


11.82 


11.96 


12.09 


12.23 


12.36 


12.49 


12.63 


5.1 


5.2 


11.45 


11.58 


11.71 


11.85 


11.98 


12.11 


12.24 


12.38 


12.62 


12.66 


12.80 


5.2 


5.3 


11.60 


11.73 


11.86 


11.99 


12.13 


12.27 


12.40 


12.53 


12.67 


12.71 


12.8-'. 


5.3 


0.4 


11.76 


11.89 


12.02 


12.16 


12.29 


12.42 


12.55 


12.69 


12.83 


12.97 


13.01 


5.4 


5.5 


11.91 


12.04 


12.17 


12.31 


12.44 


12.58 


12.71 


12.85 


12.99 


13.12 


13.25 


5.5 


3.d 


12.07 


12.20 


12.33 


12.47 


12.60 


12.73 


12.87 


13.00 


13.14 


13.28 


13.41 


5.6 


5.7 


12.22 


12.35 


12.48 


12.62 


12.75 


12.89 


13.02 


13.16 


13.30 


13.44 


13.57 


\7 


5.8 


12.38 


12.51 


12.64 


12.77 


12.91 


13.(5 


13.18 


13.31 


13.45 


13.69 


13.72 


5.8 


5.9 


I2.53;i2.66 


12.79 


12.93 


13.06 


13.19 


13.33 


13.47 


13.60 


13.74 


13.87 


5.9 


l).C 


12.69 


12.82 


12.95 


13.09 


13.22 


13.35 


13.49 


13.62 


13.75 


13.89 


14.02 


6.0 



Appendix. 



28[l 



Fable XIV. 



Comparisons of Fahrenheit and Centigrade 
(Celsius) thermometer scales. 




284 Testing Milk and Its Products. 

Table XIV. Comparisons of thermometer scales ( Continued, ) 



Fahren- 


Centi- 


Fahren- 


Centi- 


Fahren- 


Centi- 


heit. 


grade. 


heit. 


grade. 


heit. 


grade. 


4-104 


+40 


+68 


+20 


+32 


+0 


103 


39.44 


67 


19.44 


31 


—0.55 


102 


38.89 


66 


18.89 


30 


1.11 


101 


38.33 


65 


18.33 


29 


1.67 


100 


37.78 


64 


17.78 


28 


2.22 


99 


37.22 


63 


17.22 


27 


2.78 


98 


36.67 


62 


16.67 


26 


3.33 


97 


36.11 


61 


16.11 


25 


3.89 


96 


35.55 


60 


15.55 


24 


4.44 


95 


35 


59 


15 


23 


5 


94 


34.44 


58 


14.44 


22 


5.55 


93 


33.89 


57 


13.89 


21 


6.11 


92 


33.33 


56 


13.33 


20 


6.67 


91 


32.78 


55 


12.78 


19 


7.22 


90 


32 22 


54 


12.22 


18 


7.78 


89 


31.67 


53 


11.67 


17 


8.33 


88 


31.11 


52 


11.11 


16 


8.89 


87 


30.65 


51 


10. 5o 


15 


9.44 


86 


30 


50 


10 


14 


10 


85 


29.44 


49 


9.44 


13 


10.55 


84 


28.89 


48 


8.89 


12 


11.11 


83 


28.33 


47 


8.33 


11 


11.67 


82 


27.78 


46 


7.78 


10 


12.22 


81 


27.22 


45 


7.22 


9 


12.78 


80 


26.67 


44 


6.67 


8 


13.33 


79 


26.11 


43 


6.11 


7 


13.89 


78 


25.55 


42 


5.55 


6 


14.44 


77 


25 


41 


5 


5 


15.00 


76 


24.44 


40 


4.44 


4 


15.55 


75 


23.89 


39 


3.89 


3 


16.11 


74 


23.33 


38 


3.33 


2 


16.67 


73 


22.78 


37 


2.78 


1 


17.22 


72 


22.22 


36 


2.22 





17.78 


71 


21.67 


35 


1.67 


—1 


18.33 


70 


21.11 


34 


1.11 


2 


18.89 


69 


20.55 


33 


0.55 


3 


19.44 



To convert deg. Fahrenheit to corresponding deg. Centigrade: 
Subtract 32, multiply difference by 5, and divide by 9. 
Example: Which degree Centigrade corresponds to 110° F.? 110 - 82 = 

78; 78 X 5 = 390; 390 -•- 9 = 43.33. 

To convert deg. Centigrade to corresponding deg. Fahrenheit: 
Multiply by 9, divide product by 5, and add 32 to quotient. 

Example: Which degree Fahrenheit corresponds to 95.5° C? 95.5 X 9 = 
859.5; 8&9.5 -»- 6 = 171.9: 171.9 + 32 = 203.6. 



Appendix. 



285 



Table XV. Comparison of metric and customary weights and 

measures. 



Customary 

weights and 

measures. 



inch 

foot 

mile 

square inch., 
square foot .. 
square yard. 

acre 

cubic inch... 
cubic foot.... 
cubic yard... 

bushel 

fluid ounce.. 

quart 

gallon 

grain 

ounce (av. ).. 
pound (av. ) 



Equivalents in 
metric system. 



2.54 centimeters. 
.3048 meter. 
1.6094 kilometers. 
6.452 sq, centimeters. 
9.29 sq. decimeters. 
.886 sq. meter. 
.4047 hectare. 
16.387 cc. 
.0283 cub. meter. 
.765 cub. meter 
.3552 hectolitei 
29.57 cc. 

.9464 liter. 
3.78.^^4 liters. 
64.8 milligrams. 
28.35 grains. 
.4536 kilogram. 



Metric weights 

and 

measures. 



1 meter 

1 meter 

1 kilometer 

1 sq. centimeter 
1 square meter.. 
1 square meter.. 

1 hectare 

Ice 

1 cub. decimeter 

1 cub. meter 

1 hectoliter 

Ice 

1 liter 

1 decaliter 

1 gram 

1 gram 

1 kiloirram 



Equivalents in 
customary system 



39.37 inches. 
1.0936 yards. 
.6214 mile. 
.155 sq. inch. 
10.764 sq. feet. 
1.196 sq. yards. 
2.471 acres. 

.061 cubic inch. 
61.023 cubic inches. 
35.314 cub. feet. 
2.8377 bushels. 
.0338 fluid ounce. 
1.0567 quarts. 
2.(5417 quarts. 
15.43 grains. 

.035274 ounce. 
2.2046 pounds (av. 



Table XVI. Specific Gravity and Weight of one Gallon of 
Cream, in Pounds, arranged according to the per cent, of fat. 



Per cent 


Specific 


Weight of 


Per cent 


Specific 


Weight of 


of fat 


gravity 


one gallon 


of fat 


gravity 


one gallon 


m cream 


of cream 


lbs. 
8.6391 


in cream 
35 


of cream 
0.9963 


lbs. 





1.036 


8.3076 


10 


1.0243 


8.5417 


36 


0.9952 


8.2985 


15 


1.0186 


8.4938 


37 


0.9941 


8.2894 


16 


1.0174 


8.4843 


38 


0.9930 


8.2804 


17 


1.0163 


8.4749 


39 


0.9919 


8.2714 


18 


1.0152 


8.4654 


40 


0.9908 


8.2624 


19 


1.0140 


8.4560 


41 


0.9897 


8.2534 


20 


1.0129, 


8.4465 


42 


0.9886 


8.2444 


21 


1.0118 


8.4372 


43 


0.9875 


8.2354 


22 


1.0107 


8.4278 


44 


0.9864 


8.2265 


23 


1.0096 


8.4184 


45 


0.9854 


8.2176 


24 


1.0085 


8.4090 


46 


0.9843 


8.2087 


25 


1.0073 


8.3997 


47 


0.9832 


8.1998 


26 


1.0062 


8.3905 


48 


0.9821 


8.1909 


27 


1.0051 


8.3812 


49 


0.9811 


8.1821 


28 


1.0040 


8.3719 


50 


0.9801 


8.1733 


29 


1.0029 


8.3626 


51 


0.9790 


8.1646 


30 


1.0017 


8.3534 


52 


0.9780 


8.1558 


31 


1.0006 


8.3443 


53 


0.9770 


8.1470 


32 


0.9995 


8.3352 


54 


0.9760 


8.1382 


33 


0.9984 


8.3260 


55 


0.9749 


8.1294 


34 


0.9973 


8.3168 









286 Testing Milk and Its Products. 

SUGGESTIONS regarding the organization of co-operative 
creameries and cheese factories. 

When the farmers of a neighborhood are considering the 
establishment of a creamery or cheese factory, they sliould first 
of all make an accurate canvas of the locality to ascertain the 
number of cows that can be depended on to supply the factory 
with milk. The area which may be drawn from will vary 
according to the kind of factory which it is desired to operate. 
A successful separator creamery will need at least 400 cows 
within a radius of four to five miles from the proposed factory.^ 
Small cheese factories can be operated with less milk, and 
gathered-cream and butter factories generally cover a much 
larger territory than that mentioned. In all cases, however, 
the question of the number of cows contributing to the enter- 
prise must be fully settled before further steps are taken, since 
this is a point upon which success will largely depend. 

Methods of organization. The farmers should form their own 
organization, and not accept articles of agi'eement proposed by 
traveling agents. An agreement to supply milk from a stated 
number of cows should be signed by all expecting to join the 
association. When a sufficient number of cows has been 
pledged to insure the successful operation of a factory, the farm- 
ers agreeing to supply milk should meet and form an organi- 
zation. This may be done according to either of the following 
plans which have been known to give good satisfaction. 

Raising money for building and equipment. 

First. — Each member will sign an agreement to pay on or 
before a given date for a certain number of shares in the com- 
pany at dollars per share; or, 

Second. — An elected board of directors may be authorized to 

borrow a sum of money not exceeding thousand dollars 

on their individual responsibility, and the sum of cents, 

(usually five cents) per hundred pounds of milk received at 
the factory shall be reserved for the payment of this borrowed 
money. 

1 Bull. 56, Wisconsin experiment station. 



Appendix. 287 

Constitution and by-laws of a co-operative association are drawn 
up and signed by the prospective members of the association 
when it has been determined to form such an association. It 
is impossible to include in an illustration all the articles and 
rules that may be found useful in each particular instance; the 
following suggestions in regard to some of the points to be in- 
cluded in the documents are given as a guide only. It may be 
found advisable to modify them in various ways to meet the 
needs of the organization to be formed. 

After the constitution and by-laws have been drawn up and 
made plain to all the members of the association, they should 
be printed and copies distributed to all parties interested. 

Constitution 

OR 

Articles of Agreement of the Association.' 

1. The undersigned, residents within the Counties of , 

State of , hereby agree to become members of the 

Co-operative Association, which is formed for the purpose of 
manufacturing butter or cheese from whole milk. 

2. The regular meetings of the association shall be held an- 
nually on the day of the month of Special 

meetings may be called by the president, or on written request 
of one-third of the members of the association, provided three 
day's notice of such meeting is sent to all members. 

Meetings of the board of directors may be called in the same 
way, either by the president or by any two members of the 
board of directors. 

3. Ten members of the association, or three of the board of 
directors, shall constitute a quorum for the transaction of busi- 
ness. 

4. The officers of the association shall include president, sec- 
retary, treasurer, one of whom is also elected manager, and 
these officers together with three other members of the associa- 



^The following publications have beon freely used in preparing this 
constitution and by-laws : Woll, Handbook f. Farmers and Dairymen ; 
Minn, experiment station, bull. No. 35 ; Ontario Agricultural College, 
special bulletin, May 1807. See also Iowa exp. station, bull. No. 139. 



288 Testing Milk and Its Products. 

tion shall constitute the board of directors. Each of these six 
oflftcers shall be elected at the annual meeting and hold office 
for one year, or until their successors have been elected and 
qualified. Any vacancies in the board of directors may be filled 
by the directors until the next annual meeting of the association. 

5. The duties of the president shall be to preside at all meet- 
ings of the association, and perform the usual duties of such 
presiding officers. He shall sign all drafts and documents of 
any kind relating to the business of the association, and pay 
all money which comes into his possession by virtue of his 
office, to the treasurer, taking his receipt therefor. He shall 
call special meetings of the association when deemed necessary. 

In the absence of the president, one of the board of directors 
shall temporarily fill the position. 

6. The secretary shall attend all business meetings of the 
association and of the board of directors and shall keep a care- 
ful record of the minutes of the meetings. He shall also give 
notices of all meetings and all appointments on committees, 
etc. He shall sign all papers issued, conduct the correspond- 
ence and general business of the association, and keep a correct 
financial account between the association and its members. He 
shall have charge of all property of the association not other- 
wise disposed of, give bonds for the faithful performance of his 
duties and receive such compensation for his serviaes as the 
board of directors may determine. 

7. The treasurer shall receive and give receipt for all money 
belonging to the association, and pay out the same upon orders 
signed by the president and the secretary. He shall give such 
bonds as the board of directors may require. 

8. The board of directors shall audit the accounts of the 
association, invest its funds, appoint agents, and determine all 
compensations. They shall prescribe and enforce the rules and 
regulations of the factory. They shall cause to be kept a rec- 
ord of the weights and tests of the milk or cream received from 
each patronf ^e products sold, the running expenses, etc., and 
shall divide among the patrons the money due them each 
mouth. They shall also make some provision for the with- 



Appendix. 289 

drawal of any member from the association, and make a re- 
port in detail to the association at the annual meeting. Such 
report shall include the gross amount of mill^ handled during 
the year, the receipts from products sold, and all other re- 
ceipts, the amounts paid for mill?: and for running expenses, 
and a complete statement of all other matters pertaining to 
the business of the association. 

9. Among the rules and regulations to be enforced by the 
board of directors may be included some or all of the follow- 
ing: 

a. Patrons shall furnish all the milk from the cows prom- 
ised at organization of the association. 

b. Only sweet and pure milk will be accepted at the fac- 
tory, and any tainted or sour milk shall be refused. 

c. The milk of each patron shall be tested at least three 
times a month. a 

d. Any patron proved to be guilty of watering, skimming 
or otherwise adulterating the milk sent to the factory, or by 
taking more than 80 pounds of skim milk or whey for every 
100 pounds of whole milk delivered to the factory, shall be 
fined as agreed by the association. 

e. A patron's premises may be inspected at any time by 
the board of directors, or their authorized agent, for the pur- 
pose of suggesting improvements in the methods of caring 
for the milk or the cows, in drainage and general cleanli- 
ness; or to secure samples of the milk of his cows for ex- 
amination when it is deemed necessary. 

10. Any changes or amendments to the by-laws or consti- 
tution of the association must be made in writing by the 
parties proposing the same, and posted prominently in a con- 
spicuous place at the creamery, at least two weeks previous 
to their being acted upon. Such changes to be in force must 
be adopted by a two-thirds vote of the stockholders. 

11. In voting at any annual or special meeting of the asso- 
ciation, the members shall be entitled to one vote for each cow 
supplying the milk to the factory, or for each share of the 
stock owned by them, as agreed upon. 



INDEX 



The figures refer to pages in the book. 



Acid bottle, Swedish, 47. 

Acid measures, 31, 47, 54. 

Acid tester, Swedish, 67. 

Acidimeter, Devarda's, 124. 

Acidity of cream, 125, 129; esti- 
mation of, 135. 

Acidity of mill^, cause of, 119 ; de- 
termination of, 132 ; methods of 
testing, 120. 

Acidity pellets, 125. 

Adulteration of milk. 111, 115, 
244 ; calculation of, 115. 

Adulterated butter, 240, 242 ; 
cheese, 245. 

Albumen, 14 ; determination of, in 
milk, 225. 

Albuminoids, 13. 

Albumose, 14. 

Alkaline tablet test, 124 ; stand- 
ard solution of, 126 ; accuracy, 
128. 

Alkaline tabs, 136. 

American cheddar cheese, 21. 

Ames method for determining 
vrater in butter, 237. 

Amphoteric reaction of milk, 119. 

Amyl alcohol, use in cream test- 
ing, 88. 

Analysis, chemical, of butter, 231 ; 
butter milk, 228 ; cheese, 243 ; 
condensed milk, 229 ; cream, 
228 ; milk, 217 ; skim milk, 228 ; 
whey, 228. 

Appendix, 259. 

Artificial butter, detection of, 240. 

\sh, determination of, in butter, 
232 ; in cheese, 244 ; in milk, 
227. 



Babcock glassware, standard, spe- 
cifications for, 258. 

Babcock test, the, 4, 28 ; Bart- 
lett's modification, 72 ; direc- 
tions for, 20 ; discussion of de- 
tails, 37 ; for butter, 96 ; for 
butter milk, 94 ; for cheese, 97 ; 
for condensed milk, 98 ; for 
cream, 75, 180 ; for ice-cream, 
100 ; for skim milk, 90 ; for 
whey, 94 ; glassware used in, 
37 ; modifications of, 71 ; scaleo 
for weighing cream, cheese, etc., 
80, 233 ; water to be used in, 68. 

liabcock testers, 54 ; electrical, 03 ; 
hand testers, 60 ; power testers, 
61 ; steam turbine, 61. 

Bartletrs modiQcallon of Babcock 
test, 48, 72. 

Bausch and Lomb centrifuge, 72. 

Boimling test, 5. 

Bi-carbonate of soda, detection of, 
251. 

Bi-chromate of potash, 108, 168 ; 
solution of, 108. 

Blended milk, 254. 

Board of health degrees, 106. 

Boiled milk, detection of, 249. 

Boiling test, the, 242. 

Boracic acid in dairy products, 
136, 251. 

Borax in dairy products, 251. 

Butter, artificial, 12 ; detection of, 
240. 

Butter chart, 278 ; use of, 197. 

Butter, 20 ; Babcock test for, 196 ; 
chemical analysis of, 231 ; com- 
plete analysis in same sample. 



292 



Testing Milk and Its Products. 



232 ; composition of, 21, 258 ; 
creamery methods of estimating 
water in, 233 ; definition, 255 ; 
determination of ash, 232 ; case- 
in, 231 ; fat, 231 ; salt, 233, 239 ; 
water, 231 ; rapid estimation of 
water, 233 ; Ames method, 237 ; 
Cornell test, 237 ; Dean's meth- 
od, 237 ; Gray's method, 235 ; 
Irish test, 237 ; Mitchell-Walker 
test, 236 ; Patrick's method, 
236 ; Wisconsin high-pressure 
oven method, 238 ; process, 255 : 
renovated, 255 ; sampling for 
analysis, 95, 231 ; scales for 
weighing, 81, 233 ; standard, 
255 ; variations in composition, 
188 ; yield, calculation of, 187. 

Butter fat, amount due, at 12-25 
cents per lb., 272 ; conversion 
factor for, 196; definition, 255 ; 
determination of specific grav- 
ity, 240 ; volatile fatty acids, 
241 ; expansion coefficient, 36 ; 
specific gravity, 38 ; determin- 
ation, 241 ; standard, 255 ; test 
and yield of butter, 187. 

Butter making, quantities of prod- 
ucts obtained in, 21. 

Butter milk, 21 ; Babcock test for, 
94 ; chemical analysis of, 228 ; 
composition, 258 ; definition, 
255 ; specific gravity, 229. 

Calculation of adulteration of 
milk, 115; of concentration of 
condensed milk, 230 ; of milk 
solids, 109; of overrun, 195; of 
sp. gr. of milk solids, 113; of 
yield of butter, 1S7, 196, 197; 
of cheese, 199 ; of dividends at 
creameries, 203 ; at cheese fac- 
tories, 213 ; of percentages, 172. 

Calibration of glassware, 48 ; 
Trowbridge method, 51. 

Carbohydrates, 15. 

Casein, 13 ; determination of, in 
butter, 231; in cheese, 243; in 



milk, 3, 226; Hart's method, 
226. 

Centrifugal machines, 54. 

Chamberland filters, 14. 

Cheddar cheese, American, 21 ; 
composition, 258. 

Cheese, 21 ; Babcock test for, 97 ; 
calculating yield of, from casein 
and fat, 201 ; from fat, 199 ; 
from solids not fat and fat, 200 ; 
composition, 21, 258 ; chemical 
analysis of, 243 ; definitions, 
256 ; determination of ash, 244 ; 
casein, 243 ; fat, 243 ; water, 
243 ; "filled," detection of, 244 ; 
quality of, from milk of differ- 
ent richness, 211 ; sampling, 97 ; 
standard, 256 ; yield, calculation 
of, 199 ; yield of, from milk 
with 2.5 to 6 per cent, fat and 
lactometer readings from 26 to 
36, 281 ; yield of, and quality of 
milk, relation between, 200. 

Cheese factories, calculating divi- 
dends at, 213 ; co-operative, 216, 
285 ; proprietary, 215. 

Cholesterin in milk, 18. 

Citric acid in milk, 18. 

Cleaning solution for test bottles, 
43. 

Cleaning test bottles, 40 ; appa- 
ratus for, 41, 44. 

Cochran's test, 5. 

Coloring matter in milk, detection 
of, 247. 

Colostrum milk, 18 ; composition 
of, 258. 

Combined acid bottle, 47. 

Composite samples, 151 ; care of, 
170 ; case for holding, 166 ; 
methods of taking, 160 ; pre- 
servatives for, 167. 

Composite sampling, accuracy of, 
167 ; use of drip sample, 162 ; 
McKay sampler, 165 ; Michels' 
cream sampling tube, 165 ; one- 
third sample pipette, 166 ; Sco- 
vell sampling tube, 163 ; tin dip- 
per, 160. 



Index. 



293 



Composition of butter, 258 ; but- 
ter milk, 258 ; cheese, 258 ; col- 
ostrum milk, 258 ; condensed 
milk, 258 ; cream, 258 ; milk, 18, 
258 ; milk ash, 17 ; skim milk, 
258;. whey, 258. 
Condensed milk. 22 ; analysis of, 
229 ; composition of, 258 ; de- 
termination of concentration, 
230 ; of sp. gr. of, 230 ; testing 
of, 98. 
Control samples of milk. 111. 
Conversion factor for butter fat, 

19C. 
Conversion tables for thermome- 
ter scales, 282 ; for weights and 
measures, 284. 
Cornell test for determining water 

in butter, 237. 
Cows, number of tests required in 
testing, 147; single, sampling 
milk of, 150; when to test, 149. 
Cream, 19, 228 ; acidity of, 125, 
129 ; Babcock tost for, 75, 180 ; 
bottles, 79 ; care in sampling, 
necessity of, 182 ; clotted, 255 ; 
definition, 255 ; determination of 
acidity of, 125, 135 ; errors of 
measuring in testing, 76 ; evap- 
orated, 255 ; fat in 1 to 1000 
lbs., testing 12 to 50 per cent., 
270 ; gelatin in, detection of, 
249 ; overrun, 194 ; pasteurized, 
detection of, 248 ; scales, 80 ; 
separator, 19 ; gathering and 
sampling, 185 ; separation of, 
influence of temperature, 185 ; 
sour, determination of acidity, 
125 ; spaces, 170 ; specific grav- 
ity, 77, 102 ; standard, 255 ; 
starch in, 250 ; testing, 75 ; 
eliminating meniscus in, 87 ; 
testing outfit, 181 ; testing at 
creameries, 17G ; tests, correct 
readings of, 85, 87 ; use of 5 cc. 
pipette in sampling, 86 ; use of 
milk test bottles, 84 ; test bot- 
tles, 79 ; weight of, delivered by 



17.6 cc. pipette, 77 ; weight of 
1 gal., 285. 

Creameries, calculating dividends 
at. 203 ; co-operative. 205. 28.') ; 
cream testing at, 176 ; proprie- 
tary, 204. 

Creamery inch, 1, 177. 

Curd test, the Wisconsin improved, 
137. 

Dean's method for determining 
water in butter, 237. 

Definitions of milk and its prod- 
ucts, 254. 

DeLaval's butyrometer, 8. 

Devarda's acidimeter, 124. 

Diameter of tester and speed re- 
quired, relation between, 57. 

Dividends, calculating at cheese 
factories, 215 ; at creameries, 
205 ; of both milk and cream at 
the same factory, 211. 

Dividers, u.se of, 37. 

Double-necked test bottles, 92 ; 
value of divisions of, 93. 

Draining-rack for test bottles, 42. 

Eichler's Siiurepillen, 125. 
Expansion coefficient of butter fat. 
30. 

Failyer and Willard's test, 4. 

Farrington's alkaline tablet test, 
124. 

Fat, 11 ; color of, an index to 
strength of acid used. 67 ; con- 
tent, causes of variation in, 146 ; 
determination of, in butter, 231 ; 
in cheese, 244; in milk, 221; 
globules, 11 ; Gottlieb's method 
for determining, 222 ; influence 
of temperature on separation of, 
69 ; measuring of, in cream test- 
ing, 86 ; in milk testing, 35 ; 
pounds in 1-10.000 lbs. of milk, 
testing, 3 to 5.35 per cent., 266 ; 
speed required for complete sop 
aration of, 59. 



294 



Testing Milk and Its Products. 



Fat-saturated alcohol, use in 

cream testing, 88. 
Fermentation test, the, 139. 
Filled cheese, detection of, 245. 
"Fitch's Salt Analysis," 239. 
Fjord's centrifugal cream test, 8. 
Fluorids, detection of, 252. 
Food, influence of on quality of 

milk, 144, 146, 150. 
Food standards. Government, 254. 
Fool pipettes, 46. 
Formaldehyd, detection of, 252. 
Frozen milk, sampling of, 27. 

Gauges of cream, 176. 

Gelatine in cream, detection of, 
249. 

Gerber's acid-butyrometcr, 7 ; fer- 
mentation test, 139. 

Glassware used in the Babcock 
test, 37 ; calibration of, 48. 

Globulin, 15. 

Glycerids of fatty acids, 13. 

Glymol, use in cream testing, 88. 

Goat cheese, 14. 

Gottlieb method, the, 222. 

Government food standards, 254. 

Gray's test for water in butter, 
235. 

Grain-feeding, heavy, influence of, 
on quality of milk, 155. 

Hand separator cream, gathering 

and sampling, 185. 
Hand testers, 60. 
Hart's test for casein in milk, 

226. 
Hemi-albumose, 14. 
Herd milk, variations in, 153 ; 

ranges in variations of, 154. 
Hydrostatic balance, 82. 
llypoxanthin, 18. 

Ice-cream, test of, 100 ; definitions, 
255 ; apparatus for determin- 
ing overrun, 101. 

Immoi'sion refractometer, use of 
for detection of watered milk, 
245. 



Introduction, 1. 

Iowa station test, 5. 

Irish test for water in butter, 287. 

Kumiss, 256. 

Lactic acid in milk, 16. 

Lactocrite, 5, 7, 

Lactose, 15. 

Lactochrome, 18. 

Lactometer, the, and its applica 
tion, 102 ; bi-chromate, influence 
on, 108 ; cleaning of, 108 ; de- 
grees, 101 ; N. Y. board of 
health, 106, 261 ; Quevenne, 
103 ; reading the, 106 ; testing 
accuracy of, 108 ; time of tak- 
ing readings, 107. 

Lecithin in milk, 18. 

Leffmann and Beam test, 5. 

Legal standards for milk, 112, 259. 

Liebermann's method, 5. 

Macroscopic impurities in milk, 
250. 

Manns' test, 121 ; testing outfit, 
124. 

Marschall acid test, 131 ; rennet 
test, 141. 

McKay sampling tube, 165. 

Measuring fat column in testing 
cream, 86, 87 ; in testing milk, 
35. 

Mercury, calibration with, 51 ; 
cleaning, 52. 

Metric and customary systems of 
weights and measures, compar- 
ison of, 284. 

Michels' cream sampling tube, 165. 

Milk, acidity of, 119, 132; albu- 
men in, 12 ; adulteration of, 
111 ; amphoteric reaction of, 
119 ; ash, composition of, 17 ; 
blended, definition, 254 ; boiled, 
detection of, 249 ; casein in, 
13 ; chemical analysis of, 217 ; 
cholestei-in in, 18 ; churned, 
sampling of, 24 ; citric acid in, 
18; colostrum, 18; composition 



Index. 



295 



of, 10, 18, 258; composite 
Bampllng of, 160 ; condensed, 22, 
98, 258 ; correction table for 
specific gravity, 262 ; defini- 
tions, 254 ; detection of coloring 
matter, 247 ; of preservatives, 
135, 251 ; determination of acid- 
ity, 132 ; of ash, 227 ; of casein 
and albumen, 223 ; of fat, 221 ; 
of milk sugar, 226 ; of solids, 
221 ; of specific gravity, 217 ; 
of water, 220 ; fat in, 11 ; from 
cows in heat, 112 ; from sick 
cows, 112 ; from single cows, 
sampling of, 150 ; variations in, 
142 ; frozen, sampling of, 27 ; 
gases, 18 ; hypoxanthin, 18 ; lac- 
tochrome, 18 ; lactose, 15 ; leci- 
thin, 18; legal standards, 112, 
259 ; macroscopic impurities, 

250 ; mineral components, 17 ; 
partially churned, sampling of, 
24 ; pasteurized, detection, 248 ; 
preservatives, detection, 136, 

251 ; quality of. Influence of food, 
155 ; of heavy grain feeding, 
155 ; of pasture, 156 ; method of 
Improving, 158 ; sampling, 23, 
29; scale, Richmond's, 110; 
scales, 150 ; serum, 10 ; skim- 
ming, 116 ; solids, 10 ; calcula- 
tion of, 109 ; specific gravity of, 
113 ; souring of, 15 ; sour, sam- 
pling of, 26 ; standards, 112, 
254 ; sugar, 15 ; tests for adul- 
teration : nitric acid test, 245 ; 
sp. gr. of skim milk, milk serum, 
or whey, 247 ; testing on the 
farm, 142 ; testing purity of, 
137 ; urea, 18 ; water, 11 ; water- 
ing of, 116 ; detection of, by re- 
fractometer, 245 ; watering and 
skimming, 117. 

Milk test, a practical, need of, 1 ; 
requirements of, 6 ; bottle, use 
of, in testing cream, 84 ; Rus- 
sian, 71. 

Milk tests, Babcock, 4, 6 ; Beim- 
llng (Lefifmann and Beam), 5; 



Cochran, 5 ; DeLaval butyrome- 
ter, 8 ; Failyer and Willard, 4 ; 
Fjord, 8 ; foreign, 7 ; Gerber 
acid-butyrometer, 7 ; introduc- 
tion of, 4 ; lactocrite, 5, 7 ; Lie- 
bermann, 5 ; Lindstrom, 9 ; 
Nahm, 5 ; Parson, 4 ; Patrick 
(Iowa station test), 5; Rose- 
Gottlieb, 5, 222 ; sal-method, 5 ; 
Schmied, 5 ; Short, 4 ; sin-acid, 
7 ; Thomer, 5 ; Wollny refracto- 
meter, 9. 

Milk products, composition of, 19, 
258. 

Monrad rennet test, the, 140. 

Milk testing, 28 ; on the farm, 142. 

Mitchell-Walker test, 236. 

Nahm's test, 5. 

N. Y. board of health lactometer, 

105 ; degrees corresponding to 

Quevenne lactometer degrees, 

261. 
Nitric acid test for adulteration of 

milk, 245. 
Non-fatty milk solids, 10. 
Normal solutions, 121. 
Nuclein, 14. 

OflScial tests of cows, 150. 

Oil-test churn, 2, 177. 

Oleomargarine, detection of, 240, 
242 ; cheese, detection of, 245 ; 
tests for artificial coloring mat- 
ter in, 243. 

One-third sampling pipette, use of, 
166. 

Organization of co-operative cream- 
eries and cheese factories, sug- 
gestions concerning, 285. 

Overrun, 190 ; calculation of, 195 ; 
factors infiuencing, 190 ; table, 
199, 280 ; from cream, 194 ; 
from milk, 190. 

Parsons' test, 5. 

Pasteurized milk or cream, detec- 
tion of, 248. 



296 



Testing Milk and Its Products. 



Pasture, influence on quality of 

milk, 156. 
Patrick's test, 5 ; method for de- 
termining water in butter, 236. 

Percentages, average, methods of 
calculation, 172 ; fallacy of aver- 
aging, 171. 

Phenolphtalein, 122. 

Physician's centrifuge, use of, in 
milk testing, 72. 

Pipettes, 30. 45 ; proper construc- 
tion of points, 45 ; proper meth- 
od of emptying, 31 ; calibration, 
54. 

Pooling system, 3. 

Potassium bi-chromate, 168. 

Power testers, 61. 

Preservaline, 135, 251; detection 
of in milk, 135, 251. 

Preservatives, for composite sam- 
ples, 167 ; in milk, detection of, 
135, 251. 

Primost, 14. 

Process butter, detection of, 242. 

Proteose, 14. 

Quevenne lactometer, the, 106 ; 
degrees corresponding to scale of 
N. Y. board of health lactome- 
ter, 106, 261. 

Readings of cream tests, 86 ; of 
milk tests, 35. 

Recknagel's phenomenon, 107. 

Refractometer, Wollny, 9 ; immer- 
sion, use of for detection of 
watered milk, 245. 

Reichert number, 242. 

Reichert-Wollny method, 241. 

Relative-value tables, 209, 274. 

Rennet tests, 140. 

Renovated butter, detection of, 
242 ; boiling test, 242 ; Water- 
house test, 242. 

Reservoir for water in Babcock 
test, 70. 

Richmond's milk scale, 110. 

R6se-Gottlieb's method, 5, 222. 

Russian milk test, the, 71. 



Salicylic acid, detection of, 252. 
Salt, estimation in butter, 239. 
Sampling cheese, 97 ; milk, 23, 29 ; 

milk from single cows, 150. 
Sampling tube, for cream, 181 ; 

McKay, 165 ; Michels, 165 ; Sco- 

ville, 163. 
Scales for weighing cream, 80 ; 

milk. 150. 
Schmied method, the, 5. 
Scovell sampling tube, 163. 
Serum solids, 10. 
Short's test, 4. 
Siegfeld's modification of Babcock 

test, 72. 
Sinking fund, 209. 
Separator cream, 19. 
Skimming of milk, detection of, 

116. 
Skim milk, 19 ; Babcock test for, 
90 ; chemical analysis of, 228 ; 
composition of, 258 ; condensed, 
255 ; definition, 255 ; sp. gr., 
102 ; test bottles, 92. 
Solids not fat, 10 ; formulas for 
calculating 110; tables show- 
ing, corresponding to 0-6 per 
cent, fat and 26-36 lactometer 
degrees, 263. 
Sour milk, sampling, 26 ; analysis, 

228. 
Space system, the, 176. 
Specific gravity, 102 ; cylinders, 
103, 107 ; influence of tempera- 
ture, 104 ; of butter fat, deter- 
mination of, 240 ; of butter milk, 
229 ; of condensed milk, 230 ; of 
milk, 217 ; of milk solids, 113 ; 
of sour milk, 229 ; temperature 
correction table, 262. 
Speed required for complete sepa- 
ration of fat, 57 ; ascertaining 
necessary speed in Babcock 
test, 59. 
Spillman's cylinder, 131. 
Standard measure for calibrating 

test bottles, 50. 
Standards for Babcock glassware, 
257, 258. 



Index. 



297 



standards of purity, Government, 
for milk and its products, 254. 

Starch in cream, 250. 

Steam turbine testers, 61. 

Stokes' acidity pellets, 125. 

Storch's test, 248. 

Sulfuric acid, 64 ; table showing 
strength of, 67 ; testing strength 
of. 65. 

Sweetened condensed milk, Bab- 
cock test for, 99. 

Swedish acid bottle, 47. 

Swedish acid tester, 67. 

Tank for cleaning test bottles, 43. 

Temperature of turbine testers, 
36 ; of fat when tests are read, 
36^ of milk, influence on tests, 
152. 

Test bottles, 80, 38 ; apparatus 
for cleaning, 41. 44 ; calibration, 
48 : cleaning, 41 ; croam, 79 ; 
draining-rack for, 42 ; marking, 

39 ; skim milk, 92 ; rack for use 
in creameries and cheese facto- 
ries, 166 ; tank for cleaning. 43. 

Testers, 54 ; ascertaining speed of, 
58 ; electrical, 63 ; hand, 60 ; 
power. 61. 

Testing cows, number of tests re- 
quired during a period of lacta- 
tion, 147. 

Testing milk and its products, 1 ; 
on the farm, 142. 

Test sample, size of, 153. 

Tests of cows, official, 150. 

Thermometer scales, comparison 
of, 282. 

Thorner's method, 5. 

Total solids In milk, 10 ; determi- 
nation, 221. 

Trowbridge method of calibration, 
49. 

Turbine testers, 61 ; hot, errors in. 
36. 



Volatile acids in butter fat, de- 
termination, 241. 

Wagner skim milk bottle, 94. 

Waste acid jar, 40. 

Water, calibration with. 48 ; deter- 
mination of, in butter, 231, 233 ; 
in cheese, 243 ; in milk, 220 ; 
reservoir for, 70 ; to be used in 
the Babcock test, 69. 

Waterhouse test, 243. 

Watering of milk, detection of, 
116 ; watering and skimming, de- 
tection of, 117. 

Weights and measures, comparison 
of metric and customary, 284. 

Westphal balance, 219. 

Whey, 22 ; Babcock test for, 94 ; 
chemical analysis, 228 ; composi- 
tion, 258 ; definition, 256. 

WInton cream bottle, the, 79. 

Wisconsin creamery butter, sum- 
mary of analyses, 189. 

Wisconsin curd test, the improved, 
137. 

Wisconsin high-pressure oven test, 
for water in butter, 238. 

Wollny refractometer, 9. 

World's Fair breed tests, compo- 
sition of butter from, 188 ; vari- 
ation in quality of milk, 153, 

Yield of butter, calculation of, 
187, and butter fat test, 187 ; 
from different grades of milk, 
192; table showing, from 1 to 
10,000 lbs. of milk, testing 3 to 
5.3 per cent., 278. 

Yield of cheese, calculation of, 
199 ; relation between, and qual- 
ity of milk, 200 ; table showing, 
corresponding to 2.5 to 6 per 
cent, of fat, with lactometer 
readings of 26 to 36. 281. 



THE "FACILE" 

Iron Frame Babcock IVIilk Testers 




FACILE STEAM TURBINE TESTER 
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Sizes 6, 8, 10 and 12 Bottle 



D. H. Burrell & Co., Little Falls, N. Y. 

Creamery, Cheese Factory and Dairy Apparatus and Supplies 
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Testing Specialties 

We furnish everything for the commercial testing of milk and 
its products. No other concern makes so varied a line. Among 
our specialties we describe the following : 

Wizard Turbine Babcock Tester 

Made for factory use. Enclosed case ; top turbine 7 inches in 
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20th Century Hand Babcock Tester 

For dairy use and where steam pressure is not available ; en- 
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bottle size for 9 in. bottles. We also furnish this tester In 
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Electric Drive Babcock Tester 

Same as Wizard and 20th Century tester except that it is 
driven by electric motor mounted on top of case. Furnished in 
any regular size, and with motor as required according to the 
current used. 

''Official" Hand Babcock Tester 

For dairymen and travelers. Made to clamp to table or 
bench or may be permanently fastened with screws ; bottles set 
in deep brass pockets ; noiseless cut spur and worm drive. 
Made in two and four bottle sizes. 

Hart Casein Test 

Hand power, similar to 20th Century tester ; made for six and 
twelve tubes. Furnished with all necessary equipment. 

Farrington iVIoisture Test 

Wisconsin High Pressure Oven principle. Two styles of oven 
furnished ; the Farrington tests from two samples upward at 
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The Ames Moisture Test 

Paraffine method. Complete outfit consists of jacketed par- 
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C. p. Salt Test 

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JUNKET CREAM TABLETS for Ice Cream Manufacturers 
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New Style Torsion Cream Te^t Scales 

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^ Gream- Weighing Scale 

FOR USE IN CONMECTION 
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THIS SCALE Is especially designed for 
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In. long: porcelain plates 3 in. square. 

PRICE $10.00 

Manufactured by HENRY TROEMNER, 911 Arch St., PHILADELPHIA, PA. 




All Text and Reference Books used in 

AMERICAN DAIRY SCHOOLS 

may be obtained from 
MENDOTA BOOR COMPANY. Madison, Wisconsin 

SEE LIST ON FOLLOWING PAGE 



The Accuracy and Quality of 
Nafis Scientific Glassware 

have insured its steady use in the 
largest Creameries. Cheese Fac- 
tories and Condensing Plants as 
well as Dairy Schools and Experi- 
ment Stations. 

When so ordered, Test Bottles and Pipettes 
are made in accordance with the specifications 
formulated by the U. S. Bureau of Stand- 
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Write for Catalogue 




LOUIS F. NAFIS 



544 Washington Blvd. 



Ghicago, Illinois 



BOOKS 



The following books on dairying and related topics will be sent, postage prepaid, 
on receipt of the price given 



FaiTington-Woll, Testing Milk and Its Products, 
Twenty-third ed. Madison, Wis., 1915, 304 pp 1 25 

Woll, Handbook for Farmers and Dairymen. Fifth ed. 

New York, 1912, 488 pp 1 50 

Woll, Productive Feeding of Farm Animals. Phila- 
delphia, Pa., 1915, 362 pp 1 50 

Grotenfelt-Woll, Principles of Modern Dairy Practice. 
Third ed., revised. New York, 1910, 286 pp 2 00 

Wing, Milk and Its Products. New ed., rev. New 
York, 1912. 433 pp 1 50 

Fleischmann, The Book of the Dairy. London and New 

York, 1896, 344 pp 4 00 

Snyder, Dairy Chemistry. New York, 1906, 190 pp.— 1 25 

Meyer. Modern Butter-Making. Madison, Wis., 1910, 

306 pp. 1 50 

Eckles. Dairy Cattle and Milk Production. New York, 

1911, 342 pp. 1 60 

Larsen and White, Dairy Technology. New York, 1913, 
298 pp. 1 50 

Michels, Creamery Butter-Making. Lansing, Mich., 

1904. 271 pp 1 50 

Russell, Dairy Bacteriology. Fifth ed. Madison, Wis., 

1903, 214 pp 1 00 

Conn, Practical Dairy Bacteriology. New York, 1907, 
340 pp. 1 25 

Gurler, The Farm Dairy. Chicago, 1909, 164 pp 1 00 

Decker, Cheese Making. Rev. ed. by F. W. Woll. Madi- 
son, Wis., 1909, 211 pp 1 75 

Winslow. The Production and Handling of Clean Milk. 

Second ed. New York, 1909, 207 pp 3 25 

Belcher, Clean Milk. New York, 1903, 146 pp 1 00 

Monrad, ABC in Buttermaking. Winnetka. 111., 1900, 

68 pp. 50 

Monrad, ABC in Cheesemaking. Winnetka, 111., 1900, 

68 pp. 50 

Schoenman, Butter Fat and Dividend Calculator 2 00 

Henry, Feeds and Feeding. Tenth ed. Madison, Wis., 

1910, 613 pp. 2 25 

Plumb, Types and Breeds of Farm Animals. New York, 

1907, 563 pp. 2 40 

Jensen, Essentials of Milk Hygiene. Second ed. Phila- 
delphia. 1909. 275 pp 2 00 

Craig, Judging Live Stock. Tenth ed. Des Moines, 
la., 1912, 193 pp 1 50 

King, Physics of Agriculture. Fourth ed. Madison, 

Wis.. 1907, 604 pp 1 75 

Boss, Instructions for Traction and Stationery Engi- 
neers. Minneapolis, 1906, 319 pp 1 25 

MENDOTA BOOR CO., Madison, Wisconsin 



LIBRARY OF CONGRESS 




